Updated Nov. 2, 2011 at 8:55 p.m.

More than three thousand Occupy Oakland protesters shut down the Port of Oakland, the nation's fifth busiest port, late Wednesday afternoon.

The protesters stopped traffic into and out of the port. About 200 workers arriving at the port for their 7 p.m. shift were told to go home, according to Craig Merrilees, communications director for the International Longshore and Warehouse Union. "They couldn't work. The port was closed," Merrilees said.

Some protesters surrounded trucks trying to leave the Port, while others stood nearby singing, "this land is made for you and me." A few marchers climbed on top of shipping containers.

Union members in yellow vests were scattered throughout the crowd, directing traffic and trying to prevent confrontations among protesters and between protesters and truckers.

Truck driver Jose Umana of Rodeo was trying to leave the Port around 4 p.m. when protesters blocked his path.

But he wasn't angry with the demonstrators.

Two women stood on the hood of his truck cab holding up a sign that says, “Disarm Cops. Arm Feminists,” as Umana honked his horn.

“The protest is good. The economy is bad for everyone. And I have ladies on my truck,” he said.

Around 7:15 p.m., a group of 200 hundred protesters surrounded a longshoreman driving a white pick-up truck who was trying to leave the port.

Some began attacking his car, while others yelled, “Peaceful. Peaceful.”

After about 10 minutes, the protesters let the longshoreman leave.

At a news briefing shortly after 5 p.m., Omar Benjamin, the Port's executive director, pleaded for demonstrators to "let our 99%" get home to their families.

"We ask that the marchers allow our Port workers safe passage home," Benjamin said.

In a statement, the Port said it will "resume operations when it safe and secure to do so."

At 3:30 p.m., the Port sent employees at its main office near Jack London Square home.

Interim Police Chief Howard Jordan said there is "a minimal police presence" at the protest, but he said the department has "sufficient resources."

A total of 4,500 people are participating in the demonstration, according to Jordan.

At the press conference, Oakland's City Administrator Deanna Santana pleaded with protesters: "No fires, no vandalism, no throwing bottles or rocks or human waste at police officers."

The Port was one of many businesses that gave employees permission to leave early.

Santana sent an email to city employees at about 3:15 p.m., allowing them to go home.

Earlier Wednesday afternoon, Santana said Oakland was open for business and encouraged people to “shop Oakland.”

For most of the day, the police presence at the protests remained "minimal," according to Jordan. And the protests remained largely peaceful.

But shortly after 2 p.m., small groups of vandals dressed entirely in black began smashing some store windows.

At the Whole Foods Market near Lake Merritt, protesters broke a window near the front door, according to Ashley Colberson, a customer service representative. Pictures from news outlets show the word "strike" spray-painted onto one of the store's windows. After the incidents, the store shut down for the day.

At 20th and Webster, the window of Chase bank branch had been smashed in. A hand-written sign taped on the shattered glass read: “We are better than this.”

At the Clorox Headquarters, protesters broke windows adjacent to a Wells Fargo Bank.

Oakland police said five busineses, mostly banks, were vandalized. According to Jordan, 60-70 anarchists "dressed in all black and wearing a handkerchief or mask over their face" were responsible for the damage.

There are no reports of any injuries, Jordan said.

Paul Junge, public policy director for the Oakland Metropolitan Chamber of Commerce said, "It's a difficult day for doing business."

While most city employees remained on the job, 360 teachers in the Oakland Unified School District teachers skipped school to join the strike, the district said. About 280 of those teachers had made arrangements with OUSD for substitute teachers days before the strike. But when another 80 teachers called in sick or otherwise did not show up on Wednesday, the district scrambled to find administrators and other qualified personnel to fill in for the day.

The district said 15 administrators and 300 substitute teachers filled in Wednesday.

"Some students were left without a substitute so the district had them join other classes," said Troy Flint, a district spokesman.

OUSD will have to spend about $60,000 from its general fund to cover the cost of substitute teachers for the day, Flint said. At two elementary schools -- Bridges Academy and Esperanza, most teachers were absent. Student absenteeism was not a factor on Wednesday, Flint added.

The last time the district had a walkout this size was April 29, 2010, when more than 1,900 of the district's 2,000 teachers held a daylong strike as part of a labor dispute, Flint said.

"It is definitely a strain, but we were able to make sure there were substitutes for nearly every classroom," he said.

Demonstrators began arriving in Frank Ogawa Plaza in front of City Hall before 9 a.m., forcing AC Transit to reroute buses in downtown Oakland.

By 11 a.m., hundreds of protesters were in the plaza listening to speakers, while hundreds more began marching in the streets, moving from bank to bank, to express their outrage at taxpayer-funded bailouts for financial institutions.

They briefly stopped at a Wells Fargo branch, which closed for the day, before heading to the Citibank Financial Center, which closed its doors as demonstrators began blocking the bank’s entrance.

Wells Fargo has nine branches in Oakland and the decision to close the one branch was a result of the proximity of demonstrators to the store, bank spokeswoman Holly Rockwood said.

"We are deeply committed to the city of Oakland and are one of the top private employers in the city," Rockwood said.

"We are open to discussing issues with Occupy Oakland leaders in the community," she said.

By 12:45 marchers had blocked the intersection of 20th and Franklin and erected a banner reading: “Occupy banks.” Using their bodies and yellow caution tape, protesters blocked the entrances to a Chase branch and a Wells Fargo branch at the intersection.

The general strike had attracted a very diverse crowd.

Essence Harden, 27, a graduate student at UC Berkeley, has attended several Occupy Oakland events. “I have mostly been at night. During the day now, there are more people, more families, more students. It’s definitely a different feel,” she said.

Mayor Jean Quan told reporters at a morning press briefing, held at the city's Emergency Operations Center: "We're hoping to give you a boring day."

Around 9 a.m., rumors circulated among the protesters and on Twitter that the Port was closed, because longshoremen had not come to work. But both the Port and the International Longshore and Warehouse Union, which represents longshoremen, said the port was open for business.

"Our seven terminals are operational. Of course, the situation changes minute by minute," said Robert Bernardo, a spokesman for the Port of Oakland.

"The Port is absolutely not shutdown. A small number of workers didn't show up, but the Port is fully operational," said Roy San Filippo, a spokesman for the International Longshore and Warehouse Workers Union.

Jose Rubalcada, a truck driver from Madera, said he has been waiting in line at the Port for an hour. It usually takes him an hour to get into and out of the Port.

“I heard the Port is closed, but now it is moving,” Rubalcada said. “So I don’t know.”

In the plaza, a group of Service Employees International Union members were in a tent at the plaza, assembling noisemakers for the march to the Port of Oakland this afternoon.

Dwight McElroy, the president of the Oakland chapter of the SEIU, says that 300 to 400 of his union's members will be out in the street by the end of the day.

A little before 9 a.m. protesters had started closing off Broadway and 14th street. About 50 to 60 people crowded the intersection, including cab driver Brad Newsham, 60, who lives in Oakland.

"I got stuck here, what can I do?" Newsham said.

On the plaza, demonstrators stood on the back of a flat bed truck that was broadcasting music. They exhorted the crowd to tell their stories of the 99% -- the Occupy movement's term for people they believe are shut out of a political system that they say favors the wealthy.

Lisa Bettles and Josephine Rivera stood in the shadows of the truck, listening to the music and the speakers.

Neither Bettles nor Rivera had been to an occupy event before; the events of Oct. 25 when police fired tear gas at protesters brought them out, they said.

The women are organizers for Local 2 of the Hotel and Restaurant Workers' Union.

"I was really surprised what happened," said Rivera, who works with a hotel union, Local 2, "Those were the working people."

"Or," said Bettles, "the people who want to be working."

Many protesters said that the General Strike was their first foray into the Occupy Movement.Trisha Barau, 25, a graduate student at UC Davis who lives in Oakland, was one such first-timer. "I'm excited about the General Strike, I want to be a part of it," she said, noting that fears of police action had kept her away on previous days. "I can't afford to be arrested, in so many ways," she said, noting that she had taken a half-day off of school to attend.

Two high school seniors, Gabe Scholl, 17, and Louis Lubow, 17, travelled to Oakland from Pleasanton. Both were cutting school, with the permission of their parents, and both planned on leaving the protest before nightfall. "We're learning way more here than in school," said Scholl, who was getting attention for his Kim Kardashian-themed sign.

"We'll be back," said Lubow, grinning in the sun.

Queena Kim, Reyhan Harmanci, Zusha Elinson, John Osborn, Andy Wright, Jennifer Gollan, Matt Smith and Shoshana Walter contributed to this report.