Several people, including at least one police officer, have been killed in a shooting around a New Jersey grocery store across the Hudson River from Manhattan.

The incident prompted a security lockdown of area schools on Tuesday afternoon (local time), officials and local media said.

Jersey City Mayor Steven Fulop told a news conference that there were multiple people dead inside the store, where suspects reportedly had holed up and exchanged gunfire with law enforcement in a standoff that lasted for hours.

Several news media outlets including The New York Times, reported six people were dead, citing unnamed law enforcement sources, but Reuters could not immediately confirm the number of casualties.

The New York Times said the dead included a police officer, three victims who were in the store and two suspected gunmen.

Local media also reported the shooting unfolded at or near the JC Kosher Supermarket, though a city official told reporters there was no evidence the bloodshed was terror-related.

Two more police officers and a civilian were wounded in the shooting but were in stable condition, the Hudson County Prosecutor’s Office posted on Twitter.

The deceased officer was a married father of five, NBC New York reported.

SOUND ON: Jersey City sounds like a war zone; ALL schools on lockdown, police tell media to leave the area – https://t.co/AIGMupF1k7 pic.twitter.com/6wvtJYNaYc

— Breaking911 (@Breaking911) December 10, 2019

The standoff prompted a massive law enforcement deployment with local SWAT teams and federal agents rushing to the scene, as well as emergency services from the neighbouring New York City Police Department.

All schools in Jersey City, which faces Manhattan across the Hudson River, were placed on lockdown which was lifted later in the afternoon, according to the mayor and local media.

US President Donald Trump said on Twitter: “Just received a briefing on the horrific shootout that took place in Jersey City, NJ. Our thoughts & prayers are w/ 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.”

Just received a briefing on the horrific shootout that took place in Jersey City, NJ. Our thoughts & prayers are w/ 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.

— Donald J. Trump (@realDonaldTrump) December 10, 2019

-AAP