Numerous dockworkers, who load and unload cargo vessels, refused to cross the picket line at the port as a show of solidarity with the protesting workers.
"These service workers have effectively shut down the port," said Jack Heyman, a retired longshoreman from Oakland who chairs the International Longshore and Warehouse Union's transport workers solidarity committee.
Dozens of truck drivers decided not to interrupt the protest.
"What can you do?" David Soria, a driver for Modesto-based Rocha Transportation, said as he waited to drop off a shipment of wine. "My company told me to stay, so I'll stay. And wait."
Kos-Read said it was unfortunate that truckers were forced to stop work and wait in the rain.
The port handles roughly about 2.3 million cargo containers a year, generating about $300 million in revenue. Officials, however, say the facility is $1.3 billion in debt.
The service union, which represents electricians, clerical workers, security personnel and janitors, claimed the port is withholding requested financial information. The union also said port officials have implemented unilateral changes during bargaining sessions.
"We're showing you that if you don't take us seriously, we have the ability to shut down the port," said Gary Jimenez, a union vice president.
The protest marked the latest work stoppage at the port within the past 12 months. Occupy Oakland demonstrators shut it down twice last year.