LYNN – Officials said nobody was injured but six adults were displaced after a three-alarm fire on Collins Street Saturday. Meanwhile, the cause of the blaze remains under investigation.Firefighters responded at 1:04 p.m. Saturday to 7 Collins St. and found heavy smoke and heavy fire conditions at the two-and-a-half story wood home, Lynn District Fire Chief Arthur Richard said Sunday. Firefighters declared a working fire at 1:08 p.m., while second and third alarms were rung at 1:10 and 1:29 p.m., respectively.Forty-five firefighters from Lynn, Peabody, Salem, Saugus and Swampscott were present at the scene, while jakes from Revere, Chelsea, Melrose, Winthrop and Marblehead provided coverage at local firehouses, Richard said. The chief said the fire ignited the two-story back porches of the Collins Street home, while burning embers ignited parts of adjacent 7 Wayne Ave. While the Collins Street home was uninhabitable; the Wayne Avenue home was primarily damaged from exposure to the flames, Richard said.Six adults in two families who lived in the Collins Street home received temporary shelter and money for food and clothes from the Red Cross.Richard said crews left the scene at 3:03 p.m. Saturday and the cause of the blaze remains under investigation.