Passengers at New York’s John F. Kennedy Airport Terminal 4 wait for flights, Monday, Jan. 8, 2018. The Port Authority of New York and New Jersey said Monday it will investigate the water pipe break that added to the weather-related delays at the airport and will “hold all responsible parties accountable.” (AP Photo/Richard Drew)

Officials at the Port Authority of New York & New Jersey apologized to travelers Monday and said they would investigate the cause of a water main break that flooded a busy international terminal at John F. Kennedy Airport, causing delays for thousands of passengers.

Flight operations resumed Monday, with significantly fewer cancellations and delays reported. However, officials urged passengers to check with their airline before heading to the airport.

Port Authority Executive Director Rick Cotton said the agency, which oversees airport operations, would conduct a thorough investigation. While the water main break appeared to be weather-related, Cotton said officials would examine whether “any other failures” contributed to the problem. He said the pipe that burst was an internal fixture, but apparently had not been weather-proofed.

“What happened at JFK Airport is unacceptable, and travelers expect and deserve better,” he said in a statement.”The Port Authority is committed to providing the highest caliber of service to all travelers and we will hold those responsible accountable for any shortcoming we find.”

The break happened just before 2 p.m. Sunday in the airport’s Terminal 4, which serves roughly 34 international and domestic carriers. It also serves at Delta’s international hub. The terminal is managed by a private operator that includes Schiphol U.S.A., the American subsidiary of a Dutch company that manages airports in the Netherlands.

The break was particularly troublesome because it came just days after several thousand flights were canceled following the massive “bomb cyclone” storm that brought snow, harsh winds and frigid temperatures to much of the Northeast. Most flights out of JFK were grounded and many international arrivals were diverted to other airports, including Dulles International and Baltimore-Washington International airports as the storm closed in.

Travelers took to Twitter to voice their frustration, posting shots of unclaimed bags. Officials at Delta Airlines said they were working to reunite people with their bags and have set up a special hotline for JFK passengers at 1-888- 977-1005.