Police say nine teenagers were injured when two suspects opened fire on a crowd of young people standing outside a Northern California house as a party was ending.

The San Francisco Chronicle reports eight teenagers were shot and one was trampled Sunday by the frantic crowd running away from the home in Vallejo.

Vallejo Police Spokesman Lt. Kevin Barlett says all victims are in stable condition. He says one was shot in the torso and others had femurs broken by bullets.

He says that one of the shooters had a mask and that officers found several spent bullet casings on the street.

No arrests have been made.

Barlett says investigators are trying to determine a motive in the attack.