San Dimas, Calif. ? A small private plane slammed into a Fourth of July crowd on the banks of a park lake, killing at least one and injuring 10, firefighters said.

Six of the injured were critical, Los Angeles County Fire Capt. Brian Jordan said.

The twin engine plane crashed at Frank G. Bonnelli Regional Park, about 30 miles east of Los Angeles, where hundreds of people were celebrating the Fourth of July.

It was unknown how many of the injured were on the plane and how many were on the ground.

Authorities said it was possible the plane was trying to make it to Brackett Field, a small nearby airport.