Agents with the FBI have pulled over a car on a highway in Brooklyn and were questioning the vehicle's occupants in connection with the investigation into the New York City bombing that injured 29 people, authorities said.
Agents stopped "a vehicle of interest in the investigation" at 8:45pm on Sunday (local time), 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 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 speak about the ongoing investigation.
No one has been charged with any crime and the investigation is continuing, Langmesser said.
The bomb that rocked a bustling Manhattan neighbourhood contained residue of an explosive often used for target practice that can be picked up in many sporting goods stores, a federal law enforcement official said, as authorities tried to unravel who planted the device and why.
The discovery of Tannerite in materials recovered from the Saturday night explosion may be important as authorities probe whether the blast was connected to an unexploded pressure-cooker device found by state troopers just blocks away, as well as a pipe bomb blast in a New Jersey shore town earlier in the day.
Governor Andrew Cuomo, touring the site of the blast in Manhattan's Chelsea neighbourhood, known for its vibrant arts scene and large gay community, 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.