WASHINGTON (AP) — Federal safety officials say they will investigate an engine fire that was discovered on a United Airlines Boeing 737 Max after the plane landed in Newark, New Jersey.

The National Transportation Safety Board disclosed the investigation Friday, when it issued a preliminary report on the June 28 incident. No one was injured.

Boeing declined to comment, referring inquiries to the NTSB and United, which said it too was investigating.

One of the plane’s two engines caught fire after the plane completed a flight from Fort Lauderdale, Florida.

Pilots said they noticed a fire-warning indicator for the left engine as they taxied to the gate at Newark Liberty International Airport. They shut down the engine and discharged a bottle of fire retardant, and the warning indicator flicked off, according to the NTSB.

There was no smoke or fire coming from the engine, but the plane was towed to the gate, where maintenance crews saw signs of fuel leaking from the engine, and heat damage inside the engine cover, the NTSB said.

The NTSB kept the engine for its investigation. Federal Aviation Administration records indicate the plane was built in late 2020.

The flight carried 179 passengers and five crew members.

The NTSB said the investigation will include representatives from Boeing, engine maker CFM International, United Airlines and the FAA.