Witnesses say they heard a loud boom before seeing flames coming out of the engine of an United Airlines plane which left San Francisco International Airport for Japan Monday afternoon.

Officials at SFO said a United Flight 837, a four-engine Boeing 747 flying from SFO to Narita International Airport, had to shut down one of its four engines and was returning to the airport. No report on if the plane has yet landed safely.


ebola _united newark

“Just saw fire come out of an engine of a plane taking off from SFO. A united plane,” tweeted Sam Smith around noon. Smith, who said he was in his office in San Bruno, said the plane had flames coming out of the left side of the engine, and that there was a loud bang. “It looked like it was going to land.” “Plane was at a low altitude – 10-20 ft flame out of engine for 2 seconds,” he said. He said he didn’t see any smoke or hear any sirens. h/t nbc

Twitter user @djreed also tweeted around the same time: “Just watched United plane engine catch fire out of SFO.”

United Airlines did not immediately return calls for comment.