New York - Authorities questioned several people early on Monday as they worked to determine whether there was a connection between several explosive devices found in two states in two days.
An explosion rocked a bustling Manhattan neighbourhood on Saturday night, and an unexploded pressure cooker device was found blocks away; there was a pipe bomb blast earlier on Saturday in a New Jersey shore town; and five explosive devices were found near a New Jersey train station late on Sunday.
On Sunday night, FBI agents in Brooklyn stopped "a vehicle of interest in the investigation" of the Manhattan explosion, according to FBI spokeswoman Kelly Langmesser.
She wouldn't provide further details, but a government official and a law enforcement official who were briefed on the investigation told The Associated Press that five people in the car were being questioned at an FBI building in lower Manhattan.
The officials spoke on condition of anonymity because they were not authorised to talk about the ongoing investigation.
No one has been charged with any crime, and the investigation is continuing, Langmesser said.
Democratic Governor Andrew Cuomo, touring the site of Saturday's blast that injured 29 people in Manhattan's Chelsea neighbourhood, said there didn't appear to be any link to international terrorism. He said the unexploded pressure cooker device appeared "similar in design" to the first bomb, but did not provide details.
On Sunday, a federal law enforcement official said the Chelsea bomb contained a residue of Tannerite, an explosive often used for target practice that can be picked up in many sporting goods stores. The discovery of Tannerite may be important as authorities probe whether the two New York City devices and the pipe bomb at the Jersey shore are connected.
Cellphones were discovered at the site of both bombings, but no Tannerite residue was identified in the New Jersey bomb remnants, in which a black powder was detected, said the official, who wasn't authorised to comment on an ongoing investigation and spoke to the AP on condition of anonymity.
Authorities said the Manhattan bombing and New Jersey pipe bomb didn't appear to be connected, though they weren't ruling anything out. The pipe bomb exploded in Seaside Park, New Jersey, before a charity 5K race to benefit Marines and sailors. The race was cancelled and no one was injured.
Late Sunday, five suspicious devices were found near a train station in Elizabeth, New Jersey. Elizabeth Mayor Christian Bollwage said the devices were found in a bag in a trash can by two men who reported seeing wires and a pipe coming out of the package. One of the devices exploded as a bomb squad used a robot to try to disarm it. No injuries were reported.
There was no immediate word on whether the devices were similar to those in nearby Seaside Park or New York City.
Officials haven't revealed any details about the makeup of the pressure cooker device, except to say it had wires and a cellphone attached to it. On Sunday night, police blew up the device, rendering it safe. A forensic examination of the device will be sent to the FBI Laboratory at Quantico, Virginia, police said.
Homemade pressure cooker bombs were used in the Boston Marathon attacks in 2013 that killed three people and injured more than 260.
On Sunday, a team of five FBI agents searched an Uber driver's vehicle that had been damaged in the Manhattan blast. The driver had just picked up three passengers and was driving along 23rd Street when the explosion occurred, shattering the car's windows and leaving gaping holes in the rear passenger-side door.
The Chelsea explosion left many rattled in a city that had marked the 15th anniversary of the 9/11 attacks only a week earlier and that was scheduled to hold a United Nations meeting Monday to address the refugee crisis in Syria.
Witnesses described a deafening blast that shattered storefront windows and injured bystanders with shrapnel in the mostly residential neighbourhood on the city's west side.
One New Yorker, Anthony Stanhope, was in his apartment when the blast went off nearby. He said at first he thought it was thunder and lightning.
"Then all of a sudden, car horns went off, and I thought, 'Oh, my God, this isn't lightning. This is too loud," Stanhope said. "This is a bomb."
AP