A flight instructor and student were killed in a helicopter crash near Interstate Highway 680 in Alameda County this morning after the aircraft hit power lines and ignited a fire, according to Federal Aviation Administration spokesman Ian Gregor.

The Schweizer 269 helicopter crash-landed onto Sheridan Road in an area of the county between Fremont and Sunol at 12:32 a.m., Gregor said. It is unknown who was piloting the helicopter.

The aircraft was owned by a San Mateo-based company, according to Gregor.

When the helicopter hit the power line, it caught fire, killing its occupants, according to Gregor.

The scorched two-seat aircraft sat on the roadway several hours after the crash.

"This thing is pretty badly burnt," Alameda County sheriff's spokesman Sgt. J.D. Nelson said from the scene.

A grassfire ignited by the crash burned between 3 and 5 acres of vegetation on the highway's right-hand shoulder, Nelson said.

Fremont firefighters remained on the scene this morning after controlling the grassfire around 2:30 a.m., a fire dispatcher said.