PHILADELPHIA (CBS) - Philadelphia police are searching for a gunman after a man was shot in the face while driving in North Philadelphia late Monday night. Police believe the 28-year-old man was heading east on the 1400 block of Saint Luke Street when he was gunned down, just after 11 p.m.

Police say two shots were fired at the man's Chevy Malibu. One shot shattered the driver's side window and struck him in the cheek, while the other lodged in his throat area.

Witnesses say the man then opened his door and fell to the ground, where other drivers and passers-by provided aid before emergency responders arrived. Medics rushed the victim to the hospital, where he's in critical condition.

Authorities believe the man was following his wife, who was driving in another car.

"We believe that they were together in another neighborhood and they left where they were in separate vehicles," said Philadelphia Police Chief Inspector Scott Small. "At one point they got separated - at Broad and Saint Luke when the vehicles were separated - that's when the male got shot."

Police are checking surveillance cameras while trying to figure out a motive.