A pedestrian was seriously injured when he was struck by a vehicle at the Massachusetts Avenue connector ramp to Interstate 93 Monday night, State Police said. Troopers responded at 8:40 p.m. and found the victim, a man who appeared to be in his 30s, State Police spokesman David Procopio said in an email. Police are attempting to identify the victim, who was taken to Boston Medical Center in critical condition. The vehicle that hit the man was taken to the State Police Tunnels Barracks in South Boston for examination. Troopers were interviewing witnesses and the driver and will determine if criminal charges are warranted.