New York (CNN) Operations at New York's JFK airport are beginning to get back to normal after several days of failures that crippled operations and upset passengers.

First a " bomb cyclone " stranded some travelers for days. Then "a serious breakdown" in communications forced passengers to sit on tarmacs for hours.

Now the New York airport is scrambling to clean up after a water main burst, sending customers fleeing into the 13-degree cold Sunday.

Terminal 4 at JFK International Aiport was inundated after the pipe burst Sunday.

"What occurred this weekend is completely and totally unacceptable," Port Authority Executive Director Rick Cotton said in a press conference Monday afternoon. The Port Authority of New York and New Jersey oversees transportation services and facilities in the New York City area, including JFK airport.

The water main disaster happened Sunday afternoon in Terminal 4 -- "the major gateway for international arrivals at JFK airport," the airport's website says.

On Monday morning, much of the flooding had receded. But hundreds of passengers' suitcases were soaked -- including long-delayed luggage from last week's weather calamity.

A water pipe that feeds the Terminal 4 sprinkler system ruptured.

Reygie Papasin, 32, arrived at JFK from the Philippines and was scheduled to fly to Miami on Monday.

"I just hope I can get my luggage," Papasin said. This is his first time in the United States.

Cotton -- who became executive director of the Port Authority in August -- said the Port Authority is investigating what went wrong over the weekend.

The Port Authority will review airport operations from the start of the winter weather, through the "inability" of international flights being able to arrive at gates in a timely manner into Monday.

Independent investigators and experts will be a part of that process, Cotton said.

As of Monday afternoon, the majority of flights were operating on or close to schedule, said Huntley Lawrence, the Port Authority's aviation director.

While Terminal 4 was fully open Monday, one entrance was blocked as a massive industrial-size fan tried to dry up the damage.

Pipe was not weather-protected

The pipe that burst was an important one -- it fed the Terminal 4 sprinkler system. Moments after the rupture, sheets of water cascaded from the ceiling onto passenger waiting areas.

The Port Authority said Terminal 4 is privately operated. The authority said it will "hold those responsible accountable for any shortcomings we find."

"While the water pipe break that occurred appears to be weather-related, we have launched an investigation into the incident to determine exactly what occurred and why an internal pipe was not weather-protected."

Port Authority launches investigation into water pipe break at @JFKairport. https://t.co/jOZVppTdAN pic.twitter.com/qgYb8xgrx2 — Port Authority NY&NJ (@PANYNJ) January 8, 2018

The Port Authority said delays could last for days. As of Monday evening, more than 120 flights to and from JFK were canceled for the day, according to FlightAware.com , a flight tracking website.

At least 280 flights to and from JFK were delayed Monday.

'A serious breakdown'

The severe weather forced JFK to close Thursday as a wicked nor'easter tore through the region.

The airport reopened Friday, and operations went smoothly that day, Cotton said in a Sunday evening press conference.

But on Saturday, "a serious breakdown" occurred because the terminal operators and the airlines didn't coordinate to ensure enough gates were available for incoming and outgoing aircraft. As a result, some passengers report sitting on the tarmac for hours before they could deplane or have their plane take off.

Frigid weather also caused equipment failures on the ground and in the aircraft, Cotton said. Baggage claim areas became backed up, planes were filled to capacity because of earlier delays and employees didn't show up for work because of the weather, he said.

Passengers are getting frustrated as they try to locate baggage #Chaos #JFK pic.twitter.com/KaEzf6Yz4w — Conor (@conorspudmoran) January 7, 2018

During Monday's press conference, Cotton focused on the lack of coordination between international airlines and the private terminal operators. The domestic terminals, he noted, did not experience the same delays.

"We intend to identify what went wrong, why it went wrong, where there were failures of communication, where there will failures of coordination, and we intend to fix it," he said.

Airlines and terminal operators had been directed "to immediately expedite the return of all baggage to passengers."

International terminal operators intend to reunite passengers still in New York City with lost baggage by Tuesday morning, he said.

Sen. Chuck Schumer of New York said JFK officials should have foreseen some of the problems.

"Look, when it's as cold as it was we'll cut the airport a little slack," he said.

"But what happened at JFK was way beyond cutting a little slack. It seemed almost everything broke down, it seemed like a disaster. Whether it's the runways not being plowed, whether it's the baggage machines that transport the baggage freezing, whether it's not notifying people what's going on. ... They should've been much, much better prepared -- plain and simple."

Travelers had complained about delays and baggage problems even before the water leak occurred Sunday.

Emillio Mesa traveled from Los Angeles to New York City and said he hadn't seen his baggage for 13 hours.

"The luggage pile just keeps growing," he posted on Instagram. "It's a fire hazard now. New flights are coming in, and there's no space!"