PEABODY-Fire investigators spent several hours Tuesday trying to determine the cause of a two-alarm fire that destroyed an abandoned gas station on Main Street Monday night.”They’re still down there working the scene,” said Peabody Fire Chief Steve Pasdon late Tuesday afternoon, adding that an official cause has not been determined.However, officials are still eyeing the possibility the flames may have started by homeless who frequently seek shelter at the old Souza’s Citgo station at the corner of Howley Street.Pasdon said Monday the fire started in the rear of an adjoining garage.”We have a homeless issue in the back,” he said.Fire Capt. Jay Dowling said firefighters came to the gas station on Friday to put out a trash barrel fire in the exact same area as Monday’s blaze and homeless people allegedly started it.”It’s something that we’ve known about,” said Dowling, referring to the homeless issue.There were no people on the property when firefighters arrived to put out Monday’s fire, Dowling added.Pasdon said firefighters found acetylene tanks, which are highly explosive, in the garages but said the fire had not spread to them. Those containers should not have been on the property, he said.”It was an accident waiting to happen,” said Rhonda McKinnon, an employee of McDonald’s restaurant across the street who says homeless people frequent the area behind the gas station.”I don’t know all of their names, but I see them come into McDonald’s a lot,” McKinnon said. “There are a lot of homeless people around here, but I don’t want to point any fingers? I’m glad nobody was hurt.”The Item reported in August that city officials hope to build a new CVS Pharmacy at the abandoned gas station, at 174 Main St., sometime soon.Pasdon said a cost estimate of the damage has not been determined.