A gunman sporting a rifle and body armour opened fire in a supermarket in Buffalo, New York, killing at least 10 people before being taken into custody Saturday afternoon (local time), law enforcement officials told The Associated Press. 

Details on the number of additional people shot at the Tops Friendly Market and their conditions weren't immediately available. The two officials were not permitted to speak publicly on the matter and did so on the condition of anonymity. 

Investigators believe the man may have been livestreaming the shooting and were looking into whether he had posted a manifesto online, the official said. The official cautioned the investigation was in its preliminary stages and that authorities hadn't yet discerned a clear motive, but were investigating whether the shooting was racially motivated. 

The supermarket is in a predominately black neighbourhood, about 5km north of downtown Buffalo. The surrounding area is primarily residential, with a Family Dollar store and fire station near the store. 

Police speak to bystanders while investigating after a shooting at a supermarket in Buffalo, New York. Photo / AP 

Buffalo police confirmed the shooter was in custody, but did not identify the suspect. Police officials and a spokesperson for the supermarket chain did not immediately respond to messages from the AP seeking comment. 

Witnesses reported the gunman was wearing military-style clothing in addition to the body armour, one of the officials said 

Braedyn Kephart and Shane Hill, both 20, pulled into the parking lot just as the shooter was exiting. They described him as a white male in his late teens or early twenties sporting full camo, a black helmet and what appeared to be a rifle. 

"He was standing there with the gun to his chin. We were like what the heck is going on? Why does this kid have a gun to his face?" Kephart said. He dropped to his knees. "He ripped off his helmet, dropped his gun, and was tackled by the police." 

Bystanders gather under an umbrella as rain rolls in after a shooting at a supermarket in Buffalo, New York. Photo / AP 

Police closed off the block, lined by spectators, and yellow police taped surrounded the full parking lot. Mayor Byron Brown and Erie County Executive Mark Poloncarz were at the scene late Saturday afternoon, gathered in a parking lot across the street from the Tops store and expected to address the media. 

More than two hours after the shooting, Erica Pugh-Mathews was waiting outside the store, behind the police tape. 

"We would like to know the status of my aunt, my mother's sister. She was in there with her fiance, they separated and went to different aisles," she said. 

"A bullet barely missed him. He was able to hide in a freezer but he was not able to get to my aunt and does not know where she is. We just would like word either way if she's okay." 

Governor Kathy Hochul tweeted that she was "closely monitoring the shooting at a grocery store in Buffalo," her hometown. She said state officials have offered help to local authorities. The Erie County Sheriff's Office said on social media that it ordered all available personnel to assist Buffalo police. 

Attorney General Merrick Garland was briefed on the shooting, Justice Department spokesperson Anthony Coley said. 

The shooting came little more than a year after a March 2021 attack at a King Soopers grocery in Boulder, Colorado, that killed 10 people. Investigators have not released any information about why they believe the man charged in that attack targeted the supermarket. 

- Carolyn Thompson, Michael Balsamo and Dave Collins, AP