New York City ? Detectives swept through the streets of east Harlem on Friday, searching for three teens suspected of setting fire to a homeless man, leaving him fighting for his life.

Police said Felix Najera, 48, a Mexican immigrant, suffered burns over at least 40 percent and possibly as much as 75 percent of his body, including his face, chest, arms and abdomen. He was in critical condition Friday night at New York-Presbyterian Hospital/Weill Cornell Medical Center, police said.

Early Friday morning, Najera was sleeping on a cardboard box in front of the Iglesia Cristiana Betania church, when one teen lit his pants on fire with a cigarette lighter, police said. Najera jumped up, “causing him to be engulfed in flames,” said Sgt. Carlos Nieves, a New York Police Department spokesman.