A pallet of Tesla batteries, a McLaren business office and a Ford pickup truck went up in flames Sunday morning in a shared south Palo Alto parking lot.

Palo Alto dispatchers received a call shortly before 5:30 a.m. about a possible illegal bonfire in the lot at 4190 El Camino Real, near the Arastradero Road intersection, fire Capt. Ryan Stoddard said. When firefighters responded, they saw the pickup truck, the batteries and the small building that houses the McLaren office all on fire.

"It was hard to say which of these started it," Stoddard said.

The fire occurred at the parking lot behind three dealerships: McLaren, Volvo and Tesla. The burning truck was positioned near the ramp that was close to the McLaren office but just over the property line, Stoddard said. Firefighters from Palo Alto and Mountain View attacked the fire from two sides, stretching lines from El Camino Road and from Arastradero Road, through the Walgreens parking lot.

"Then it was just surround and drown," Stoddard said.

Firefighters battled the blaze for several hours and knocked it down by 8 a.m. Smoke was still visible from the street as the batteries continued to smolder.

The small detached structure in the middle of the lot that housed the McLaren business office was completely destroyed.

One firefighter suffered minor injuries during the operation. The firefighter was transported to the hospital, treated and released, Battalion Chief Marc Muzzi said Monday.

Numerous Palo Alto police cars also arrived to the scene to investigate the fire site. Stoddard said Sunday that investigators looked into arson as a possible cause, but Muzzi said Monday it was no longer under consideration after a preliminary investigation.