The NYPD Bomb Squad rushed to JFK Airport on Sunday when customs agents found a box that contained a grenade, police and law-enforcement sources said.

The weapon was later found to be inert.

The emergency call came in around 9:45 a.m. when US Customs and Border Protection agents in Building 250 — a mailing facility — at the Queens airport found a box that looked suspicious, an NYPD spokesman said. 

“They X-rayed the box and didn’t like the contents,” the spokesman said.

The box appeared to contain a grenade, and further investigation showed it actually was the weapon — although it was deemed inert, police sources said.

There was no evacuation at the New York City airport, police said.