Authorities say an off-duty Fontana police officer was at the Mobil gas station at 16925 Foothill Boulevard when he observed a van in the parking lot with a Toyota Camry parked next to it with people who appeared to be lookouts.
According to the officer, the van appeared to be sucking fuel from the underground tanks.
Police responded to the scene and detained the suspects. Officers confirmed the off-duty officer's suspicions and determined that the suspects made it look like the van was broken down and parked it over one of the access holes for the tanks.
Investigators say the suspects had been at the same gas station on Tuesday and had siphoned as much as 300 gallons of fuel over two days.
Freddrick Hunter, 38, Edward Dawson, 32, and Terry Washington, 42 were arrested and booked for grand theft.