A car was seen on fire at the exit of the tunnel leading to the arrivals area at Boston's Logan International Airport Thursday evening. Traffic in the tunnel was stopped and firefighters were moving into position to douse the blaze. Fire, police and airport officials haven't immediately given any information about the incident. There was another incident involving a Logan airport-area tunnel earlier Thursday. A backhoe got stuck in the Callahan Tunnel, which leads to the airport and Route 1A from East Boston; traffic had to be stopped to remove it.