Federal authorities on Sunday detained five people with possible links to the New York bombing, local media reported, citing unnamed law enforcement sources.

The FBI's New York branch tweeted that no one had been charged in connection with the blast in the city's Chelsea neighborhood, which injured 29 people -- but did not make mention of any arrests.

"We did a traffic stop of a vehicle of interest in the investigation," the FBI tweet said. "No one has been charged with any crime. The investigation is continuing."

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Witnesses in aftermath of New York blast

New York media said the vehicle's five passengers were in custody for questioning.

The vehicle was stopped around 9:30 pm heading east on the Belt Parkway from the Verrazano-Narrows Bridge, which connects the New York city boroughs Brooklyn and Staten Island.

The New York Daily News reported that weapons were found in the car.

The newspaper also said that one person of interest had been identified via surveillance footage, but it was not clear if he was one of the five taken into custody.

A spokesman for the New York Police Department declined to confirm the reports, only saying that the probe was ongoing.

Authorities have been on high alert since Saturday's blast.

A second bomb was uncovered by police four blocks away and defused safely, before being sent to the FBI in Virginia for forensic examination.

Hours earlier on Saturday in New Jersey, a pipe bomb exploded in a trash can on the route of a Marine Corps run before the start of the race, causing no injuries but forcing its cancellation.

On Sunday in New Jersey, rail service was suspended between Newark airport and the city of Elizabeth, amid reports that a suspicious package had been found there.

Elizabeth Mayor Chris Bollwage told journalists that two men walking near the train station had noticed a package in a waste basket and took it.

After noticing "wires and a pipe," they dropped the package and alerted police. A drone examination found that "it could be suspicious and it could be a live bomb," and FBI officials were at the site.