LYNN – Firefighters continued to douse hot spots Tuesday and were expected to remain on the property of the abandoned Nissen factory until at least this morning following a large fire that started at the Brookline Street landmark – threatening two nearby homes – shortly before 6 p.m. Monday, according to Lynn Fire Division 3 Chief Bill Curran.While the heaviest flames were extinguished late Monday night, massive debris in the building continued to ignite well into Tuesday afternoon. Curran said a small number of firefighters would be stationed at the Nissen property at 114 Brookline St. overnight Tuesday into Wednesday morning, when fire investigators can once again evaluate the situation.Curran said much of the debris fell from the roof, most of which collapsed onto the lower floors, creating pockets for hot spots to flare. The purpose of stationing the firefighters at the scene overnight is to prevent another major fire from starting, he said.”We want to have eyes on it so we can get to it before it develops into a full-scale fire again,” Curran said.The chief said the two-alarm fire became so massive that crews’ main focus was to keep the flames from spreading from the rear of the building toward the front, directly next to where two homes are located. Residents of the homes were evacuated overnight.”Those houses were completely surrounded by fire,” Curran said. “The fire was too big for us to control but we had enough water to keep it from extending into those cottages. We were very fortunate.”Nadine Donovan, who lives in one of the homes with her husband and their two school-age children, praised the LFD Monday night.”I have to say the Lynn Fire Department was incredible. Their response time was awesome,” Donovan said. “I don’t have enough good words to say about them.”Curran’s decision to pull firefighters out of the building came not long after the fire began, when some men got their feet stuck on stairs with missing risers.”They had to pull themselves over the last step to the third floor? and the fire was spreading rapidly,” Curran said. “I said, ‘I can’t take any chances’ and pulled them out of there.”Curran said that parts of the abandoned building showed its age with rotting wood, but he could tell the building was built, complete with large timbers and reinforcement beams.”At some point this building was as close to bullet-proof as you could get,” he said. “It was a very well-made building for its time.”Curran said Tuesday he was still concerned that more parts of the building could collapse under the weight of all the water used to extinguish the fire. Over 3,000 gallons of water was sprayed on the building per minute and the heaviest of the flames raged on for at least four hours. One gallon of water weights 8.33 pounds.”It’s really heavy,” he said. “That’s why we worry about collapse a lot as firefighters.”Much of the building is windowless and not all parts of the building had been thoroughly inspected on Tuesday.Investigators continued to search for areas of origin as to where the fire started. Lynn Arson Squad Investigator Lt. Dave Legere said as the fire raged Monday that the building was vacant and had no power.”I don’t think it was an accident,” Legere said. “It could be either homeless or vandals.”As Legere spoke with the Item, he was approached by railroad workers who often monitor the MBTA commuter rail tracks located directly behind the building. One of the men reported a train traveled at 60 mph over a small fire that someone lit directly on the tracks sometime last week.The man put out the small fire himself before he radioed the incident to a control center, but later realized the dispatchers never called the Lynn Fire Department, he said.The fire halted commuter rail service between Lynn and Salem and passengers had to be bussed to their destinations.Jim Blaney has lived on Brookline Street for 28 years and can still remember buying baked goods from Nissen.”They had a little thrift store where you