A Jewish supermarket was deliberately targeted in a shootout which left six people dead, the mayor of Jersey City has confirmed.
Among those killed on Tuesday afternoon was a police detective who was investigating a murder when he approached two suspects, one of whom opened fire and shot him in the head.
Jersey City Mayor Steven Fulop said a review of security camera footage led to the conclusion that the gunmen targeted the supermarket, but refused to call it an antisemitic attack.
Speaking at a news conference, Mr Fulop said the surveillance video shows the suspects' van moving slowly before stopping in front of the supermarket.
"There were multiple other people on the street so there were many other targets available to them that they bypassed to attack that place, so it was clearly that was their target and they intended to harm people inside," he said.
He added: "I didn't use the word antisemitic. Anything else is open for investigation."
The four-hour gun battle at the Jewish JC Kosher Supermarket started after the pair shot Detective Joseph Seals, 40, at a nearby cemetery.
The gunmen then drove a hired van to another part of the city and engaged police in a shootout from inside the kosher market, where the bodies of the two suspects and three civilians were later found.
Mr Fulop said two officers one block away responded immediately after hearing the shots. Both were injured in the subsequent shootout and were later released from hospital, authorities said.
Detective Seals was shot dead at around 12.30pm.
Earlier, Mr Fulop paid tribute to Detective Seals, a married father-of-five, saying he was "a great cop" and is " probably responsible for more guns being removed from the streets than any."
Police chief Michael Kelly said the officer was trying to stop some "bad guys" near the cemetery.
"Our officers were under fire for hours," Mr Kelly told a news conference on Tuesday.
Mr Kelly said when police arrived at the area of the kosher store, officers "were immediately engaged by high-power rifle fire."
A second officer was wounded after being struck in the shoulder by gunfire, and two others were injured by shrapnel, Mr Fulop said.
Public safety officials said the motive of the attack remains unclear.
"They exited the van and they proceeded to attack this location in a targeted manner," Jersey City Public Safety Director James Shea told a morning news conference.
"With the amount of ammunition they had, we have to assume they would have continued attacking human beings if we hadn't been there."
However, Mr Shea did not comment on why the market was targeted, but said the gunmen appeared to choose it rather than other people or locations on the street.
SWAT teams, state police and federal agents responded to the incident, with officers blocking off an area which included a school, the kosher supermarket and a hair salon.
All schools in Jersey City were put on lockdown.
Authorities have said the incident is not believed to be a terror attack.
US President Donald Trump tweeted: "Just received a briefing on the horrific shootout that took place in Jersey City, NJ.
"Our thoughts & prayers are [with] the victims & their families during this very difficult & tragic time.
"We will continue to monitor the situation as we assist local & state officials on the ground."