A backpack found near a New Jersey railway station exploded even as a bomb squad was attempting to disarm it, while authorities examined another suspicious package containing up to five devices, media reported on Monday.
The second package was found on Sunday night in a wastebasket outside a pub and located about 500 feet from the train trestle in Elizabeth city, Mayor Chris Bollwage said.
"Whoever threw it into the can was probably trying to get rid of it. It's not in a highly congested area," Bollwage told CNN.
Earlier, the backpack with several pipe bombs, went off when the bomb squad were investigating it, the reports said.
Bollwage confirmed that the blast was not a controlled explosion, saying it came when the robot was "cutting into the device".
There is no threat to public safety as the package is being secured and investigated.— Chris Bollwage (@MayorBollwage) September 19, 2016
The police received reports from two men who claimed they found a suspicious package with a pipe and wires coming out of it, Bollwage said.
With investigation underway, train services were suspended between Newark's Liberty Airport and Elizabeth, while New Jersey-bound Amtrak trains from New York were being held at the Penn Station.
The discovery of the package came as the US remained on high security alert against terror attacks after 29 persons were wounded in a blast on Saturday in New York city and the explosion of a pipe bomb earlier on Saturday along the route of a Marine charity run in New Jersey.
Nine persons were also injured on Saturday night in a stabbing attack at a mall in the US state of Minnesota.
The incidents were being investigated as potential acts of terrorism, authorities said.