At about 5 p.m., demonstrators walked onto northbound Highway 980 from 11th Street, blocking that highway and subsequently Highway 880 in both directions, Oakland police Officer Jeff Thomason said.
Police arrested 149 people, including 10 juveniles, on suspicion of unlawful assembly, obstruction of a street, and failure to obey traffic signs, Thomason said.
During the arrests, a juvenile protester was injured when he allegedly tried to escape police by jumping off the highway and grabbing onto a tree, Thomason said. He fell to the ground below.
The juvenile was taken to a local hospital to be treated for his injuries and was later released after being cited by police, according to Thomason.
Thousands of commuters in the area were affected by the protest. California Highway Patrol Officer Nicole Pacheco said both highways were reopened by 6 p.m.
Most of the protesters on the highway were processed by Alameda County sheriff's deputies on the Jackson Street off-ramp. They were then taken to the Santa Rita and North County jails.
Alameda County sheriff's Sgt. J.D. Nelson said most of the people who were arrested will be released today, and some already were overnight.
The jails brought in extra staff to handle the large number of people, and the jails were locked down overnight to minimize problems while the protesters were being processed, Nelson said.
Most of those arrested were among the estimated 2,000 people who attended a rally at Frank Ogawa Plaza near 14th Street and Broadway that was part of a statewide "Day of Action" against cuts to California's public education system .