SAN FRANCISCO INT’L AIRPORT (KPIX 5) – A United Airlines flight from San Francisco to Australia was forced to make an emergency landing back at SFO early Friday morning after engine troubles were reported.

Flight 863 to Sydney left SFO around 11:15 p.m. Thursday night. Shortly after takeoff, people on the Boeing 787 Dreamliner said they noticed flames coming out of the left engine.

READ MORE: Support Builds for KPIX Reporter Targeted in YouTuber's Racist Remarks

“As soon as we took off, there was two loud sounds and two big sparks,” said passenger Sukbhar Jholl.

“We were about 40 minutes into our flight, we were going and then it got a little bit bumpy. They told us that we were going to turn around, the engine seized up,” said Jacob Franklin, who was also on the flight.

“Some other people were talking about there being some fire spitting out of the engine, but then we just turned around,” Franklin said.

READ MORE: Prop Gun Fired by Alec Baldwin on Movie Set Kills Cinematographer, Wounds Bay Area Director

After circling over the ocean to drop jet fuel and reduce weight, the plane arrived back at SFO around 12:35 a.m.

“We were pre-warned so it was not too nerve-wracking,” said Aman Ahuja, another passenger on the flight. “I must say the pilot and staff were reassuring that things were under control.”

There were no reports of injuries among the 259 people on board the flight.

Passengers were booked on other flights to Australia.

MORE NEWS: Former Oakland Police Captain Wounded During Fatal Shooting At Gas Station

The airline told KPIX 5 that it was a mechanical issue and that technicians are still investigating what went wrong.