A man was fatally shot in Roxbury last night, Boston police said. David Estrada, a police spokesman, said officers responded at about 8:50 p.m. to Homestead Street, and the man was pronounced dead at the scene. Estrada had no information last night on possible suspects. Earlier in the evening, two men were shot in Dorchester and taken to city hospitals with injuries that were not believed to be life-threatening, Estrada said. He said one man was found on Thetford Avenue and the other was found nearby on Washington Street at about 6:50 p.m. The shootings do not appear to be related, Estrada said.