LONG BEACH — A Jet Blue plane destined for San Francisco made an emergency return flight Tuesday to the Long Beach Airport, after the crew determined that jetliner had a mechanical problem.

The engine automatically shut down due to a mechanical failure, but it was unclear what caused the problem, officials said.

No one was injured on the 7:25 a.m. flight, which had been about 4 miles out at the time, according to airport spokesperson Stephanie Montuya-Morisky.

The plane landed back at Long Beach Airport at about 8:15 a.m., officials said.

There were 125 passengers on the flight, and they were booked on another flight, the spokeswoman said.