NEW YORK — Authorities questioned several people early Monday after car stop in Brooklyn as they worked to determine if there is a connection between an explosion that rocked a bustling New York City neighborhood, an unexploded pressure-cooker device found blocks away, an earlier pipe bomb blast at a New Jersey shore town or explosive devices found across the state near a train station.
On Sunday night, FBI agents 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 said 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 authorized to talk about the ongoing investigation.
No one has been charged with any crime, and the investigation is continuing, Langmesser said.
Governor Andrew Cuomo, touring the site of Saturday’s blast that injured 29 people in Manhattan’s Chelsea neighborhood, said there didn’t appear to be any link to international terrorism. He said the second device appeared ‘‘similar in design’’ to the first, 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 three incidents are connected.
Cell phones 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 spoke on the condition of anonymity because the official was not authorized to comment on an ongoing investigation.
Authorities said the Manhattan bombing and New Jersey pipe bomb didn’t appear to be connected, though they weren’t ruling anything out. The New Jersey race was cancelled and no one was injured.
Late Sunday, more suspicious devices were found near a train station in Elizabeth, N.J. 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. There turned out to be five devices in the bag. 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, Va., police said.
Homemade pressure cooker bombs were used in the Boston Marathon attacks in 2013.
On Sunday, a team of five FBI agents searched an Uber driver’s vehicle that had been damaged in the Manhattan blast, ripping off the door panels inside as they examined it for evidence. The driver, MD Alam, of Brooklyn, 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 terrorist attacks only a week earlier and where a United Nations meeting to address the refugee crisis in Syria was scheduled on Monday.
Witnesses described a deafening blast that shattered storefront windows and injured bystanders with shrapnel in the mostly residential neighborhood on the city’s west side.
As authorities tried to unravel who planted the device and why, one New Yorker, Anthony Stanhope, 40, knew exactly what had just happened.
‘‘I was sitting in my apartment, and all of a sudden I heard a big boom, and I thought to myself wait a minute, it can’t be thundering and lightning at this hour, and then all of a sudden car horns went off, and I thought oh my god this isn’t lightning, this is too loud — this is a bomb,” said Stanhope.
Caldwell reported from Washington. Associated Press writers Karen Matthews, Maria Sanminiatelli, Michael Balsamo, and Dake Kang in New York, and Eric Tucker and Kevin Freking in Washington contributed to this report.