SAN DIEGO — A federal investigator says the death toll in Sunday’s midair collision in Southern California has risen to five.

National Transportation Safety Board investigator Andrew Swick told KNSD-TV that four people were aboard a twin-engine Sabreliner jet that collided with a single-engine Cessna 172.

The jet was leased by military contractor BAE Systems, which said in a statement that its employees were aboard the aircraft.

Swick said the pilot of the Cessna, who was also killed in the crash, was on a cross-country trip.

Both planes were approaching Brown Field Municipal Airport in San Diego County when they collided around 11 a.m..

First responders said the wreckage was strewn across a quarter-mile area.

The crash sparked a brush fires in a remote field where the wreckage landed, authorities said.

“It appears it was a very violent crash, as you can tell by both aircraft being in multiple pieces,” said Nick Schuler, a division chief with the California Department of Forestry and Fire Protection.

First responders initially reported three fatalities, but as they inspected the wreckage which was strewn across a quarter-mile area, they determined that at least four people were killed, he said. Now that has been updated to five people killed.

The Sabreliner crashed on a grassy slope and the Cessna fell within the bounds of the San Diego National Wildlife Refuge.

Crews extinguished several brush fires where the planes came down. One firefighter was taken to the hospital after he suffered a heat-related injury, Schuler said.

Brown Field, a former Naval auxiliary air station, is in the Otay Mesa area about 15 miles southeast of downtown San Diego, near the border with Mexico.

The FAA and National Transportation Safety Board will investigate.