A mother and her baby escaped unharmed Thursday from a fast-moving fire at a Suffolk Avenue home in Brentwood when another resident, who was seriously injured, helped them out a first-floor window. Wendy Maldonado, 18, was sleeping in her bedroom with her 3-month-old daughter when the other resident, who she identified as Jesus Cabrera, knocked on the door telling her the house was on fire. She said she handed her baby out the window to Cabrera. "It was really scary," Maldonado said, "I thought I was going to get burned. . . . He's a hero to me." She and her daughter, Hayli, were not injured. The Brentwood Fire Department received the call at 11:02 a.m. for the fire at 155 Suffolk Ave. By the time the department arrived minutes later, the fire had fully engulfed the basement and first floor, Carney said. Cabrera had burns on more than 45 percent of his body and was taken by Brentwood Ambulance to Southside Hospital in Bay Shore, Brentwood Fire Chief John Carney said. The victim was later transferred to Stony Brook University Medical Center, according to a Southside Hospital spokesman. Arturo Maldonado, the owner of the home who is not related to Wendy Maldonado, was issued two violations by the Town of Islip's fire marshal; one for alterations to the basement without permits and another for change of use - improperly converting the house from its original one-family use to a multifamily dwelling, according to town officials. The cause of the blaze has not been determined, but is not considered suspicious, he said. The Suffolk police arson squad was investigating Thursday afternoon. After initial reports that residents were trapped inside, about 20 firefighters searched the home, but no one was there, Carney said, adding that 40 firefighters responded from Brentwood, Bay Shore and East Brentwood fire departments.