NEWARK — A United Airlines flight made an emergency landing at Newark Liberty International Airport this morning when its right main landing gear failed to extend, authorities said. The incident briefly shut down the airport, according to the Port Authority of New York and New Jersey.

United Airlines Flight 634 from Chicago with 53 people aboard landed safely at 9:27 a.m. at Newark, its intended destination, United spokesman Robin Urbanski said in a statement.

Passengers were evacuated and there were no injuries, according to the Port Authority. There were 48 passengers and five crew members on board.

The plane’s right main landing gear did not extend, though its nose and left main landing gear did, said Arlene Salac, a spokeswoman for the Federal Aviation Administration.

Ron Marsico, a spokesman for the Port Authority, said the incident briefly shut down the airport.

Flights have resumed but the incident has closed a runway, causing delays of up to 45 minutes for departing flights, according to the Federal Aviation Administration.

The airplane, an Airbus 319, left Chicago’s O’Hare International Airport just before 6 a.m., bound for Newark, according to the United Airlines website. Authorities did not explain what went wrong with the landing gear.

ABC news, however, showed a photograph of what appears to be the disabled plane parked on the runway, with its right wing touching the ground, surrounded by emergency vehicles.