Six people have been killed in a gunfight in Jersey City. 

Those killed in the incident in New Jersey included a police officer and two suspects, Jersey County Police said.

Two other officers were also injured, but have been released from hospital. 

Schools and shops across the city were put on lockdown as the shootout unfolded on Tuesday afternoon. 

The shooting began at a cemetery – where the officer was gunned down – before continuing at a kosher supermarket. 

Police chief Michael Kelly said five bodies were found at the shop. Three of those killed are believed to have been bystanders, Reuters reported. 

“Our officers were under fire for hours,” Kelly said.

He would not tell reporters what had started the shooting, but said he believed the police officer was killed trying to stop some “bad guys”. 

Meanwhile, authorities said they did not believe the incident was a terror attack. 

The standoff saw SWAT teams, state police and federal agents called to the scene, which was blocked off by police. 

Dozens of bystanders pressed against the police barrier to capture the action on their mobile phones, some whooping when bursts of fire could be heard.

Video shot by residents recorded loud volleys of gunfire reverberating along one of the city’s main streets and showed a long line of officers pointing guns as they advanced, yelling to bystanders: “Clear the street! Get out of the way!”

“It’s like firecrackers going off,” said Andy Patel, who works at a liquor store about three blocks away.

“They were shooting like crazy. The cops were clearing everyone off the streets.”

In a tweet, Donald Trump called the incident “horrific”. 

“Our thoughts & prayers are w/ the victims & their families during this very difficult & tragic time,” the president wrote. 

“We will continue to monitor the situation as we assist local & state officials on the ground.”