The Portland man who shot himself three times in the head with a flare gun Tuesday morning remained in critical condition Wednesday night at Maine Medical Center.

Maine State Police said the case of Daniel Abbott, 65, is being investigated as an attempted suicide.

Abbott was pulled from the cab of his pickup truck by two passers-by, one of whom used a fire extinguisher to put out a fire in the cab.

State troopers said the two prevented the fire from spreading to a propane tank in the truck’s bed. If the flames had reached the tank, the truck could have exploded. Abbott had converted his truck to propane fuel.

The incident occurred Tuesday morning in the northbound lanes of Interstate 295 in Freeport, near the Brunswick town line.