This rather unfortunate three car pile-up took place yesterday afternoon on Interstate 10 near Benson, Arizona, when a man allegedly using Tesla’s Autopilot semi-autonomous system crashed his Model S into an Arizona State Trooper’s vehicle.

The impact caused the cruiser to hit the back of an ambulance, though thankfully the latter’s occupants weren’t injured and the officer wasn’t in the vehicle at the moment of impact.

As for the driver of the Model S, a 23-year old man from Irvine, CA, he was taken to a nearby hospital with “serious but non-life-threatening injuries.” He is currently being investigated for DUI (driving under the influence), which can mean either alcohol or other substances.

Related: Police Car Read-Ended By Tesla, Authorities Believe Autopilot Was Enabled

After the incident took place, Arizona’s Department of Public Safety tweeted that the driver told troopers his Tesla was on Autopilot at the time of the collision. The AZ DPS also took this opportunity to remind the public that when you see flashing lights and vehicles stopped on the side of the road, you should slow down.

Bart Graves of the Arizona Department of Public Safety told Digital Trends that the driver of the Tesla is still under investigation and cannot comment whether or not he will be charged with a DUI, adding that “the investigation is continuing.”

This is just the latest in a long line of crashes involving Teslas and the company’s Autopilot system. Federal authorities have already investigated many similar incidents and came to the general conclusion that drivers tend to become overly reliant on this semi-autonomous system.

Photo Department of Public Safety