CORPUS CHRISTI, Texas -

The search is on for a missing tanker chief engineer in the Gulf of Mexico.

Coast Guard crews and the tanker Elia crew are looking for the man off Port Aransas after he went missing Sunday afternoon.

The missing person is a 47-year-old Russian man.

Authorities say that crew members looked throughout the ship before calling the Coast Guard for help at 1:55 p.m. The man was seen around 10:10 a.m. but could not be found after being called for at 10:30 a.m.

The boat was about 20 miles offshore on its way to the Port Aransas anchorage, according to the Coast Guard.

A MH-65 Dolphin helicopter, a 45-foot Port Aransas-based response boat and a HU-25 Falcon airplane have joined the search.

Officials say that if the man is not located before nightfall, that they will search throughout the night with an 87-foot patrol boat called the Coast Guard Cutter Amberjack.