OAKLAND -- A group of truck drivers halted commerce at one of the Port of Oakland's biggest terminals Monday to protest work conditions and the rising costs of hauling cargo out of the busy seaport.

Truckers and their supporters picketed outside three entrances to the SSA Marine terminal and effectively shut down cargo traffic because crane operators and other terminal workers refused to cross the protest line. About 100 ralliers gathered before dawn. By 9 a.m., the company that runs the terminal informed the port that it was closing down.

"We came to work, but everything's blocked," said terminal worker Cisco Paredes, adding that he and other International Longshore and Warehouse Union workers weren't entering the terminal because they felt unsafe.

The protesters -- drivers who own and operate their own trucks -- say the amount they get paid per load is the same as it was a decade ago, but they pay far more for diesel and truck maintenance.

They want fees to cover the costs of meeting air quality regulations that have become more stringent; they also want to be compensated for waiting in increasingly long lines outside congested terminals.

"We're all out here because we don't make money sitting in lines for four hours," said driver Armando Visperas, of San Jose. "It's not working out for us."

Francisco Guzman, a trucker for 22 years, said that to comply with regulations, he would have to get a new truck or install upgrades on his 2002 rig.

"They never listen to us, that's why we're here," Guzman said.

Along with the long lines, which truckers say are particularly bad at SSA Marine's terminal because of a recent merger and too few workers, new rules from the California Air Resources Board are raising the cost of being an independent truck driver.

Jose Gonzalez, of Suisun City, says he'll be forced to replace his 1999 truck at the beginning of the year.

"To keep going, I'll have to buy a $60,000-to-$70,000 truck and sell mine for $5,000," he said.

Many trucks began lining up to enter the terminals after 5 a.m., as they do every morning. Some drivers avoided the protest.

"All they're doing is hurting themselves," said one driver who gets paid hourly by the company he works for. Protesters yelled at those who appeared to ignore their blockade.

Siding with city officials, an Alameda County judge filed a temporary order last week that bars the protesters from interfering with cargo traffic. Still, the trucker group representing independent contractors put out a call to labor activists and the Occupy movement over the weekend inviting them to join them Monday. The alliance was a turnaround from November 2011, when a mass Occupy Oakland protest annoyed many blue-collar maritime workers by shutting down the entire seaport without their consent.

On Monday, a line of baton-carrying officers from the Alameda County Sheriff's Office forced protesters away from one terminal entrance. Some protesters claimed they were hit with batons.

The union representing port terminal workers said it was sympathetic to the truckers' economic plight but didn't endorse a disruptive protest.

"They're trying to use the port as an economic tool. I understand that, but the problem is they hurt the area," said Mike Villeggiante, who heads ILWU Local 10. "People looking on the outside will think it's not a reliable port."

Villeggiante added that "the problem is they're independent, and maybe they need to organize."

Truck drivers say they already self-organized through the group that staged the Monday protest, and another two-day stoppage in August, but argue they cannot unionize because they are independent contractors. Both the truckers and the longshore workers said Monday that relations between the two groups have been testy -- with truckers sometimes blaming crane workers for making them wait, and terminal workers complaining about truckers ignoring safety rules to get cargo more quickly.

Port officials said they sympathized with truckers' concerns about long waits and are striving to fix the problems.

"We believe they're raising some valid issues," said port spokesman Isaac Kos-Reed. He said the new port director, Chris Lytle, has met with some of the port's 5,000 registered truck drivers, most of whom own their own trucks, and "is doing everything he can, the port is doing everything it can, to help get them what they want."

While the recently merged SSA Terminal was the only one shut down Monday, Kos-Reed said the protests also interrupted operations at other terminals. He said it was impossible to estimate the lost revenue Monday but that economic activity at the seaport amounts to about $8 million daily. Equally worrisome, he said, was the long-term effect on the seaport's reputation as "a reliable gateway."

"The only thing that's going to help everybody in the supply chain is moving cargo faster," Kos-Reed said. "The worst thing we can be doing is having these protests and disrupting the flow of commerce. That's just going to hurt everybody."