Two terminals at New York's John F. Kennedy International Airport are resuming normal operations Monday morning after reports of shots fired prompted evacuations and grounded and diverted flights.

The reports, which led to some frightening moments for fliers Sunday night, were later determined to be unfounded and the airport was given the all-clear.

"At this time, no firearm, rounds or shell casings or other evidence of shots fired has been found," said Joe Pentangelo, a spokesman for the Port Authority of New York and New Jersey Police Department.

Police evacuated Terminal 8 around 9:30 p.m. Sunday as a precaution after receiving 911 calls about shots fired near the departures area.

Port Authority police called in officers from the New York Police Department to assist with the investigation.

A short time later, police closed Terminal 1 after they said they received additional reports of shots fired in that terminal. A highway approaching the airport also was shut down.

Passengers posted pictures and videos on Twitter that showed crowds of people gathered outside of the terminals.

Demetrius Pipkin told WPIX-TV that he was in Terminal 1 waiting for his Norwegian Airlines flight when the reports of shots fired came in.

"We were previously told to get on the floor and take cover behind any and everything we could find," said Pipkin, who described the terminal as a "madhouse" with panicky passengers eventually bolting for the nearest exists.

According to the flight tracking company, FlightAware, all inbound flights were held at their origin until 11:30 p.m. "due to security." Port Authority police said travelers should contact their carriers. They also warned of a "substantial PAPD and NYPD presence" at JFK and LaGuardia due to the investigation.

There were no injuries reported. It was not immediately clear what led to the airport scare.

