A law enforcement official says the Afghan immigrant wanted in connection with explosions in New York City and New Jersey has been taken into custody following a shootout with police officers.

The official says two officers were shot in the encounter in Linden, New Jersey. The person wasn't authorized to discuss an ongoing investigation and spoke to The Associated Press on condition of anonymity.

Authorities were looking for Ahmad Khan Rahami, a naturalized U.S. citizen from Afghanistan with an address in Elizabeth, New Jersey.

Elizabeth Mayor Christian Bollwage says county authorities told him that the officers shot in Linden are expected to be OK. He says was one was struck in a protective vest and the other in the hand.

Police released a photo of a 28-year-old immigrant wanted for questioning Monday in the bombings that rocked a New York City neighbourhood and a New Jersey shore town, and authorities said the blasts are looking increasingly like an act of terrorism with a foreign connection.

Ahmad Khan Rahami, a naturalized U.S. citizen from Afghanistan with an address in Elizabeth, New Jersey, should be considered armed and dangerous, New York Mayor Bill de Blasio said.

Police did not disclose how they zeroed in on Rahami but were known to be poring over surveillance video. At the same time, five people who were pulled over in a vehicle Sunday night were being questioned by the FBI, officials said.

The bulletin and the photo of Rahami were issued after a weekend of fear and dread in New York and New Jersey.

In addition to the blast that injured 29 people in Manhattan's Chelsea neighbourhood on Saturday, an unexploded pressure cooker bomb was found blocks away, and a pipe bomb exploded in a New Jersey shore town before a charity race. No one was injured there. On Sunday, five explosive devices were discovered in a trash can at an Elizabeth train station.

Also on Saturday, a man who authorities say referred to Allah wounded nine people in a stabbing rampage at a Minnesota mall before being shot to death by an off-duty police officer. The Islamic State group claimed responsibility.

Authorities have not drawn any connection between the violence in Minnesota and the bombings in the New York area.

Citing the FBI, New Jersey State Police said Monday that the bombings in Chelsea and the New Jersey shore town Seaside Park were connected.

New York Gov. Andrew Cuomo said as investigators gathered information, they learned there were "certain commonalities among the bombs," leading authorities to believe "that there was a common group behind the bombs."

"We want to get this guy in for questioning," de Blasio said on CNN. "We need the facts to be able to piece all this together. ... I think we're going to know a lot more in the course of the day. Things are moving very quickly."

Cuomo said investigators have no reason to believe there are further threats, but the public should "be on constant guard."

Early Monday, FBI agents swarmed an apartment above a fried chicken restaurant in Elizabeth that is tied to Rahami. The Rahami family lives in the apartment.

The restaurant, First American Fried Chicken, is owned by Rahami's father and has also employed some of his brothers, Elizabeth Mayor Christian Bollwage said.

He said Rahami's father and two brothers sued the city after it passed an ordinance requiring the restaurant to close early because of complaints from neighbours about it being a late-night nuisance.

Ryan McCann, of Elizabeth, said that he often ate at the restaurant and recently began seeing Rahami working there more.

"He's always in there. He's a very friendly guy, that's what's so scary. It's hard when it's home," McCann said.

In the immediate aftermath of the New York bombing, de Blasio and Cuomo were careful to say there was no evidence of a link to international terrorism. Both said Monday that appears to be changing.

"The more we learn with each passing hour is it looks more like terrorism," de Blasio said in an interview on NY1 News. Cuomo said on MSNBC: "Today's information suggests it may be foreign-related, but we'll see where it goes."

The White House said President Barack Obama was briefed on the investigation and planned to speak later Monday.

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 Manhattan.

The officials spoke on condition of anonymity because they were not authorized to talk about the investigation.

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.

Cellphones were discovered at the site of both the New York and New Jersey 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 authorized to comment on the investigation and spoke to the AP on condition of anonymity.

The pipe bomb that exploded Saturday in Seaside Park went off before a charity 5K race to benefit Marines and sailors. The race was cancelled.

One of the five devices found at the Elizabeth train station exploded while a bomb squad robot tried to disarm it. No one was hurt.