The explosion hit North Hollywood at about 12.30 a.m. last night, and is believed to have taken place from the pickup truck's cab.
The pickup was parked in the back of a home on the 11300 block of Miranda Street.
Sgt. Mike Kammert has said, "Police and firefighters arrived about the same time and found the truck with its roof blown open and at least one propane tank inside the truck. Kammert said the LAPD bomb squad was at the scene to determine what exploded. Officials were focusing on the propane tanks as the likely source," according to The Los Angeles Times.
He added that investigators were carrying out their work and that they were securing the area to ensure no further risks remained to locals in the region.
He said, "It'll probably be another hour or so. The bomb squad doesn't move fast, which is probably a good thing."A bomb squad was sent in to help with the investigations, and local residents were advised to find shelter.
One local witness described to NBC Los Angeles that the explosion "shook everything." One witness, Laura Weir told the network: "I heard a big loud noise and the dog started barking… The next thing I know, I see the helicopters, I see the fire department."
A propane tank was thought to have been in the pickup truck's cabin at the time of the explosion. Investigators have removed the truck to further examine it as part of their investigations.
LAPD Lt. Todd Hankel explained, "[The blast] caused extensive damage to the vehicle and damage to the surrounding buildings… We were unable to determine the source of the explosion, so we evacuated the area."
It still has not been confirmed whether the explosion was intentional or an accident. Investigations are ongoing.