The Federal Aviation Administration grounded flights across the United States on Friday after a telecommunications outage, delaying or canceling thousands of flights and stranding passengers by the thousands at airports nationwide — including New York's John F. Kennedy International, where gates filled, floors filled behind them, and answers ran out long before patience did.

Officials said the FAA acted out of an "abundance of caution" after the telecommunications issue. The agency has not said what caused the outage, and it remains unclear how long it will take for air traffic to return to normal.

At JFK, the ground stop dragged on into the night.

What happened to passengers at JFK?

Riley Alexis Holmes, 24, arrived at Kennedy Airport on Friday evening holding a ticket to Oregon, where her brother was performing in the closing night of the musical "Trolls Junior." Her 6 p.m. flight was first delayed by nearly two hours. Then it was canceled.

"I called my mom and cried, and I'm just sitting here waiting for information," Holmes told Business Insider as the disruption continued.

She was not alone in the dark. Juliana Melo, 30, of São Paulo, Brazil, was heading home to her 1-year-old daughter after a week's vacation in New York City. Her daughter was waiting in Brazil with Melo's mother and the babysitter.

"She's waiting for us in Brazil with my mother and the babysitter. So we are very nervous," Melo said at JFK, where fellow passengers crowded gates and sat on the floor with anxious faces.

Melo said her airline had not yet contacted her family to reschedule. She and her husband waited at Terminal 4 for updates.

How did the cancellations compound for business travelers?

Lennard Meijer, 49, flew from Amsterdam to New York for a one-week business trip and was due to fly back on Thursday night. Weather conditions delayed his flight, then canceled it. He was rebooked — and canceled a second time, losing access to his checked bag in the process.

After an hour and a half in line, he recovered the bag and secured a seat on a Delta flight scheduled to depart at 10:35 p.m. Friday. He said he is now afraid to check his luggage again.

"I'm half waiting for news, half deciding to take some basic stuff out of here," Meijer said. "So if I have another cancellation tonight, when I go back to the city and find another hotel last minute, I'll at least have some clothes."

He was holding out hope the flight would take off. "It's just a little exhausting being at JFK, and I can't wait to go home," he said.

What did stranded travelers learn — and not learn?

Kieran Cullen, 27, had been traveling for more than 24 hours after his overseas deployment ended. He was headed home to Jacksonville, Florida, with a layover at JFK.

"We were only expecting to be here for about five hours," he said.

Instead, the text messages started arriving. His flight was delayed 15 minutes. Then another 15. Hours later came word of the cancellation.

"So far, not a ton of information, other than just live speaker announcements discussing the centers having rotating blackouts on frequencies, but nothing specific," Cullen said. "It's over 24 hours of travel, so it's definitely a bummer."

He and his group planned to spend the night in New Jersey and hope for a flight home on Sunday — two days after their scheduled arrival.

What are the airlines offering?

Holmes said Delta told her that if she does not reschedule her flight to Oregon within 24 hours, she can claim a full refund. If she chooses to rebook instead, the money is gone. She was waiting to see whether a seat existed on any flight that would still get her to her brother's final performance.

"My first initial reaction was I was very sad, but then I was really grateful that I'm OK and that everyone hopefully is OK," she said.

For now, the mechanism behind the outage — and the timeline for recovery — rest with the FAA.