Investigators looking into the deadly shooting of a New Jersey police detective and the deaths of three others at a kosher grocery store Tuesday say there is growing concern that the market was specifically targeted, senior law enforcement sources briefed on the investigation said.

But it is too early to know what the motive is behind the attack, one senior law enforcement official said Tuesday night.

Both of the suspects, described by the sources as a still-unidentified male and female shooter, were found dead following the standoff and furious gun battle Tuesday afternoon, officials said. Three civilians were also found dead.

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Jersey City police Det. Joseph Seals, 39, was killed after police investigating a murder approached the two suspects and one of them opened fire, shooting the officer in the head, according to the sources and officials.

The pair then drove a U-Haul van to the market, and surveillance video showed them shooting right away, killing one person, and then following the gun battle with police the suspects and other victims were found inside the store, the law enforcement sources said.

Jersey City Mayor Steven Fulop tweeted Wednesday morning that CCTV footage indicates the market was targeted.

"Last night after extensive review of our CCTV system it has now become clear from the cameras that these two individuals targeted the Kosher grocery location," the mayor said in the post. "At this time we have no credible further threats from this incident but out of an abundance of caution we will be increasing our police presence in the community."

Det. Seals, who was with the Jersey City Police Department since 2006, was married and the father of five children.

Jersey City Police Chief Mike Kelly said earlier Tuesday that authorities believe Seals was shot while trying to stop the suspects. Kelly said that while he was unsure why the plainclothes detective was there, he believes it may have been related to guns.

"As the mayor alluded to, he was the leading police officer in removing guns from the street," Kelly said. "Dozens and dozens of handguns, he’s responsible for removing from the street."

Two other officers were injured, one in the shoulder and one in the body, but have since been released.

SWAT officers and first responders, including Hatzalah paramedics, who serve the orthodox Jewish community, rushed to the scene.

"Our thoughts and prayers are with the men and women of the Jersey City Police Department, especially with the officers shot during this standoff, and with the residents and schoolchildren currently under lockdown," New Jersey Gov. Phil Murphy said in a statement.

"I have every confidence in our law enforcement professionals to ensure the safety of the community and resolve this situation. Today reminds us of their bravery and the sacrifices they, and their families, make for our communities."

All schools in Jersey City were put on lockdown, while campuses in nearby Bayonne were under a "shelter in place" order as a precaution, officials said.

The Jersey City School District first tweeted about the lockdown at 1:30 p.m. and students were not reunited with parents until nearly 5 p.m.

SWAT teams with Jersey City and state police were among those responding. Federal agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives in Newark and the FBI were also on the scene.

“I can hear the gunshots. It's like firecrackers going off," said Andy Patel, who works at a liquor store about three blocks from the scene.

"They were shooting like crazy about an hour ago. Then it stopped for like 20 or 30 minutes. The cops were clearing everyone off the streets."

The two suspects had at least one long gun, which was described as an AR-type weapon, and 100 or more rounds were fired between police and the suspects, one senior law enforcement official said.

Brooklyn Borough President Eric Adams tweeted Tuesday night that he learned that two of the victims were natives of Brooklyn, and one was a current Williamsburg resident.

"This news further sharpens the pain of this #massshooting for our Jewish community. We mourn together. May their memories be a blessing," Adams said in the tweet.

New York City Mayor Bill de Blasio tweeted late Tuesday that "Although there is no credible or specific threat directed against New York City, I have directed the NYPD to assume a state of high alert.”

New Jersey Attorney General Gurbir S. Grewal said in a statement early Wednesday that his office is leading the criminal investigation and any public statements will be issued by his office.

“We continue to work closely with our federal, county, and local partners and we remain grateful for the outpouring of support from law enforcement across the region and the nation,” Grewal said. “We recognize the fear that communities rightfully feel after traumatic incidents such as these, and we are committed to providing all resources necessary to ensure the safety and wellbeing of our fellow residents.”