LYNN – Fire officials say that the cause remains undetermined for a massive blaze Sunday that left 27 residents homeless and that will require the demolition of a six-unit tenement on Western Avenue.”I finished the fire report and left the ?cause’ as still to be determined,” said District Fire Chief Lee Oliver on Monday. “One of the biggest problems is that there is so much destruction in the building and (inspectors) can’t get in to see all the damage because parts of the building are unsafe ? so we’re leaving it as open-ended, ongoing investigation.”According to Lynn Fire Department officials, the fire started on the second floor of the building around 2 a.m., Sunday morning and moved upward. All of the buildings’ residents escaped unharmed, but the building was a total loss, fire officials said. Crews arrived around 11 a.m. Sunday after the fire was extinguished to begin the cleanup effort to ready the building for demolition.Chief Oliver said that controlling the blaze “turned into quite an operation all around.”Firefighters eventually had to go into “defensive mode” and leave the building as the flames moved through the walls and ceilings and toward the roof.”The roofing material was a tar/petroleum-based product which certainly enhances the fire,” Oliver said. If (the fire) gets into that part of the structure, it is over the heads of firefighters and could come down on them.”So ladder trucks and a deck gun began spraying thousands of gallons per minute onto the flames, Oliver said. Unfortunately, that water dripped down and accumulated in the basement, toppling several oil tanks to create a foot-deep pool of oil and water, creating a hazardous materials emergency, Oliver said.The Department of Environmental Protection was called in and a contractor was on-site Sunday and Monday to pump out the resulting soup, Oliver said. But he added that cracks in the concrete foundation raise concern that some of the oil may have leached into the soil and the crews will return to the site to test the soil once the building is demolished – which was scheduled to occur first thing today, Oliver said.”The building is unsafe – there are sections of the wall that could actually fall,” Oliver said. He noted that two businesses and another multi-unit residence abut the destroyed building. “It’s going to be a very expensive operation between the demolition of the building and the environmental cleanup.”Building owner Omid Zafar said that he had not determined the cost of the damages yet nor had time to consider the future of the property.”There’s a lot of stuff that I have to deal with right now,” Zafar said Monday evening. “We’re going to go through with all of that stuff and once satisfied, then sit down and decide what direction we want to take.”Zafar said that he was working with the Red Cross to help tenants find housing, and that a few tenants had found other arrangements or were staying with family in the area. He said he was glad that the fire hadn’t been worse.”Overall, I’m happy nobody got hurt and we took care of it really quick,” he said. “We put our people to work really quick [to clean the site]. Overall it could have been worse.”