A man was shot and suffered life-threatening injuries Tuesday night in Roxbury, police said. The shooting occurred between 5 and 6 p.m. near the intersection of Massachusetts Avenue and Tremont Street, said Boston police spokesman David Estrada. The victim, who is in his 30s, was taken to Boston Medical Center, police said. Police did not have a suspect Tuesday night, but the investigation is ongoing, Estrada said. No additional information was immediately available Tuesday night.Jennifer Smith can be reached at firstname.lastname@example.org.