Three people were placed in custody after gunfire and a chase by police in Somerville Monday night, police said. Somerville police received several calls saying shots had been fired in the Gilman Street area shortly after 9 p.m., Deputy Chief Paul J. Upton said in e-mail. Officers were told several suspects had fled toward Broadway in a white vehicle. Another officer saw a vehicle headed west on Broadway toward Winter Hill and pursued it into Medford and back into Somerville. The vehicle hit a curb at Powder House Boulevard and Leonard Avenue, and the suspects fled on foot. Police found three suspects hiding in nearby yards, as well as a loaded gun. There were no known injuries, police said.