A New Jersey mayor says one of five devices found in a backpack near a train station has exploded while a bomb squad robot was attempting to disarm it.

Elizabeth Mayor Christian Bollwage said that the device exploded shortly after 12:30 a.m. Monday. The FBI was leading the investigation and working to disarm the other four devices.

There were no reports of injuries to civilians or police.

Bollwage said two men called police and reported seeing wires and a pipe coming out of a package after finding it around 8:30 p.m. Sunday.

New Jersey Transit says service has resumed after being suspended between Newark Liberty Airport and Elizabeth. NJ Transit says cross-honoring will remain in effect. 

The discovery of the suspicious package comes after an explosion rocked a charity 5K race in Seaside Park. A second blast in Manhattan injured 29 people, and an unexploded pressure-cooker device was found four blocks away.

The FBI is asking anyone with information to contact authorities at 1-800-CALL-FBI.