A man suffered a life-threatening gunshot wound in Egleston Square in Roxbury Thursday, said David Estrada, a Boston police spokesman. Boston police and Emergency Medical Services responded to 3090 Washington St. at 4:49 p.m. and found the victim with a gunshot wound to the abdomen, Estrada said. The man was taken to Boston Medical Center, Estrada said. The suspect is a male between 16 and 20 years old, and he was wearing a dark gray jacket and a white and gray baseball hat, police said. No other details were immediately available.