OAKLAND, Calif. (AP) - Police opened fire with wooden dowels, ''sting balls'' and other non-lethal weapons at anti-war protesters outside the Port of Oakland, injuring at least a dozen demonstrators and six longshoremen standing nearby.

Most of the 500 demonstrators at the port were dispersed peacefully Monday morning, but police opened fire at two gates when protesters refused to move. The longshoremen were caught in the line of fire.

The port protest was one of several anti-war demonstrations in Northern California.

Twelve people were arrested at the Concord Naval Weapons Station; seven were arrested after temporarily blocking an off-ramp from Interstate 280 in San Francisco. And in Sacramento, nine anti-war protesters were arrested when they blocked the entrance to the federal building.

About 200 of the port demonstrators later marched to the federal building in Oakland, blocking a street and chanting: ''Out of the office and into the streets! U.S. out of the Middle East!'' They were joined by Oakland City Council members Jane Bruner and Jean Quan.

''They should not have been using the wooden bullets,'' Bruner said. ''Given what's happening in the world today, we're going to be seeing more of this. And we should be prepared to handle it.''

Demonstrators said it was the first time they had been fired upon since anti-war protests started in the San Francisco Bay area more than two weeks ago.