Reports of shots fired at New York's John F Kennedy International Airport caused evacuations, grounded flights and frightening moments for fliers before the reports were later determined to be unfounded.
"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 at around 9.30pm local time on Sunday (2.30am BST Monday) as a precaution after receiving reports of shots fired near the departures area.
New York Police Department officers were called in to help with the investigation.
A short time later, police closed Terminal 1 after they said they received additional reports of shots fired in that terminal. The Van Wyck Expressway approaching the airport was also shut down.
Passengers posted pictures and videos on Twitter showing crowds of people gathered outside the terminals.
According to flight tracking company FlightAware, all inbound flights were held at their origin until 11.30pm "due to security".
Port Authority police said travellers should contact their carriers and warned of a "substantial PAPD and NYPD presence" at JFK and LaGuardia due to the investigation.
No one was injured during the airport scare.