State authorities are investigating a fatal fire at a three-story apartment building on St. Lawrence Street in Portland early Sunday. (Shawn Oullette/Staff Photographer)State authorities are still investigating what caused a fatal fire at an apartment building in Portland’s Munjoy Hill neighborhood. Firefighters responded to the three-story, four-unit building at 43 St. Lawrence St. just after 2 a.m. Sunday. Moss said their identities “will be positively determined during the autopsies.”Related Two die in Portland apartment fireThe apartment building was condemned after a city inspection on Monday, according to records provided by the city to the Press Herald. When she got up later that morning, water was still flowing on the street, Moor-Jankowski said.