(AP) - A smoking engine forced the evacuation of a plane at Newark Liberty International Airport.

United Airlines says that when Flight 2160 from San Francisco landed at about 2:30 a.m. Tuesday, the air traffic control tower notified the crew that smoke was seen coming from one of the engines.

Passengers exited the plane onto the taxiway and were bused by Port Authority of New York and New Jersey responders to the terminal.

Port Authority police say a hydraulic fuel leak is suspected as a cause for the smoke.

A few hours later, a Delta Airlines flight bound for Atlanta returned to the airport with an engine issue. A Delta spokeswoman says the plane was towed to the gate and passengers were accommodated on other flights.

No injuries were reported in either incident.