Originally Published: 07 AUG 23 03:39 ET

Updated: 07 AUG 23 12:32 ET

By Elizabeth Wolfe and Michelle Watson, CNN

(CNN) — National Transportation Safety Board investigators are headed to the spot where three people were killed after two helicopters collided in midair Sunday while fighting a fire in Southern California, an agency spokesperson told CNN on Monday.

The helicopters were among six aircraft responding to the Broadway Fire, which began Sunday after a structure fire spread to nearby vegetation in Cabazon, a community in Riverside County some 90 miles east of Los Angeles, CalFire Southern Region Chief David Fulcher said Sunday night.

A Bell 407 helicopter and a Sikorsky S-64E helicopter collided in the air, the NTSB spokesperson said.

“The first helicopter was able to land safely nearby,” Fulcher said during a news conference. “Unfortunately, the second helicopter crashed, and tragically all three members perished.”

Those killed – a contracted pilot, a CalFire division chief and a CalFire captain – are the first victims of California’s 2023 fire season, according to data from CalFire.

The Broadway Fire covered about 3 acres when firefighters responded around 6 p.m., according to a post on a joint Twitter account for CalFire and the Riverside County Fire Department. By shortly after 7 p.m., the “forward rate of spread” had been stopped, the agencies said.

A second 4-acre fire ignited by the helicopter crash has since been extinguished, Fulcher said.

“I would like to express our deepest sympathies and sorrow to the families and coworkers of the personnel,” Fulcher said. “This was a tragic loss for the community, the fire service community and CalFire and Riverside County Fire Department.”