SAN LEANDRO >> A collision between an Amtrak train and a motorcycle Sunday that left the motorcycle passenger dead and the driver critically injured happened after members of a group the cyclists were part of lifted railroad crossing arms so riders could pass through, police said Monday.

The name of the woman killed has not been released pending notification of her family.

The collision happened just before 2 p.m. Sunday near the intersection of Hesperian Boulevard and Springlake Drive, police said.

San Leandro police Capt. Abe Teng said Monday that the preliminary investigation revealed a large group of motorcyclists, roughly estimated to be about 100, was riding northbound on Hesperian Boulevard, approaching the railroad crossing at Springlake Drive.

Police have not said if the group was a part of a club or just riders who knew each other.

Teng said that as the group approached, the railroad crossing arms came down for an oncoming Amtrak train headed to Oakland.

Teng said members of the group lifted the crossing arms to allow riders through, which is when the train hit the motorcycle with the two people on it. The passenger, a woman, was pronounced deceased at the scene and the driver, a man, was transported to a hospital.

No other motorcycle riders were reported injured and police did not detain or arrest any riders at the scene.

Police said both the woman and man were wearing helmets.

San Leandro police are continuing to investigate the collision along with Amtrak investigators. Anyone with information may call San Leandro police Sgt. Ryan Gill at 510-777-0446.