BOGOTA, Colombia (AP) _ An opposition congressman was shot and killed by two motorcycle gunmen late Monday as he stopped his car at a traffic light in Medellin.

Police said Liberal Party politician Jorge Humberto Gonzalez, 48, was shot four times in the head, and died fifteen minutes after being rushed to the hospital.

Gonzalez's wife and driver were also in the car but escaped injury in the attack in Colombia's second largest city, located 160 miles northwest of Bogota, the capital.

Gonzalez was elected to congress this year, and headed a committee on labor and social policy.

In an a separate attack Monday, the bodyguard of the wife of Liberal Party leader and presidential runner-up Horacio Serpa was killed in a drive-by shooting in Barrancabermeja, 170 miles northeast of Bogota.

Police said they were investigating, but knew of no motive for either shooting.