A Tesla Model S reportedly on “Autopilot” smashed into the back of a fire truck parked at a freeway accident scene Monday morning, authorities said.

The union representing Culver City firefighters whose truck was hit around 8:30 a.m. on Interstate 405 in Culver City tweeted that the Tesla driver said he had been using Tesla’s Autopilot system, which performs automated driving tasks.

The California Highway Patrol and Culver City Fire Department confirmed the southbound Tesla had struck the fire truck, but could not immediately confirm whether the vehicle had been on Autopilot.

The fire truck had been parked in the left emergency lane and carpool lane, blocking off the scene of a previous accident, with a CHP vehicle behind it and to the side, said Culver City Fire Department battalion chief Ken Powell.

Both emergency vehicles had their lights flashing, Powell added.

The Tesla suffered significant damage, and the fire truck has been taken out of service to have body work done, Powell said.

Had any firefighters been at the rear of the truck rather than in front attending to the earlier crash, there “probably would not have been a very good outcome,” Powell said.

“It was a pretty big hit,” Powell said.

The firefighters union tweet indicated that the Tesla had been traveling at 65 miles per hour before the crash, but it was unclear to what extent the car may have slowed before striking the fire truck.

Because of the force of the impact, firefighters advised the Tesla driver that he should be taken for a medical evaluation, but he showed no significant injuries and refused treatment, Powell said.

Tesla, after the incident, said Autopilot is “intended for use only with a fully attentive driver.” The Model S owner’s manual has numerous warnings that attention to the road is vital while using Autopilot and other Tesla semi-autonomous driving functions.

The Palo Alto electric car maker’s Autopilot system made headlines in 2016 after a Model S driver was killed when his car crashed into a semi truck in Florida.

Federal road-safety officials put the blame for the fatal crash on the truck’s driver for failing to yield while entering a roadway, on the deceased Tesla driver for relying too heavily on Autopilot, and on Tesla  — the National Transportation Safety Board ruled that Autopilot contributed to the crash by allowing lengthy disengagement from the driving process, on a roadway unsuitable for the semi-autonomous-driving system.

Also, the board said, the Autopilot technology that monitors whether a driver has their hands on the steering wheel isn’t a good way to tell if the driver is paying attention.