LYNN-The investigation continues into the large fire at the former Nissen bakery on Brookline Street and now investigators are talking to neighbors who might have seen suspicious activity in and around the building leading up to Monday night’s blaze.”There’s a lot of interest with the neighbors,” Lynn Arson Squad Investigator Lt. Dave Legere said Wednesday. “They all said there are a lot of people down there.”Legere said investigators are looking into reports that people were seen lighting objects on the second floor of the building minutes before the flames erupted.”We know there are a lot of people [who congregate] down there,” he said.Legere confirmed the fire began on the second floor of the building toward the rear, causing the roof to collapse.”The first floor is basically untouched,” he said.The city granted the building owner, Dave Potter, the necessary permits to tear down the structure, Legere said. The old bakery was scheduled for demolition in order to make way for 150 condominium units before the fire started.It’s still uncertain if people were trapped in the rubble, but authorities want to search the building just to make sure.”I don’t think there is anybody down there,” Legere said.Firefighters stayed at the scene of the fire for about 48 hours because of hot spots.On Tuesday, Division 3 Fire Chief Bill Curran said he was concerned more of the building might collapse under the weight of all the water that extinguished the fire.