John Kelly, a spokesman for the Port Authority of New York and New Jersey, which manages the three main New York-area airports, said 250 to 300 passengers were evacuated from Terminal 1 at the airport around 6 p.m. and were allowed back in after 8 p.m.
The evacuation occurred after an anonymous phone caller said there was a bomb at the airport, and at the same time someone else reported an unattended bag, Kelly said.
Police checked the bag and it was not a bomb, he said.
Among the evacuated passengers was Igor Rakocevic, a Serbian professional basketball player who was trying to get home to Belgrade via Paris.
Rakocevic said a cheer erupted when security officials said passengers could return to the terminal.
Rakocevic, who posted photos of the evacuation on Twitter, said the delay would force him to miss his connecting flight to Belgrade, and he would likely not see his family until Tuesday.
"I will not see my son as planned," he said. "Probably I will lose a day."
But he added, "I'm glad nobody got hurt."