The alleged shooter was in custody, and the FBI said was investigating the attack at a supermarket in New York state as a hate crime.

Ten people are dead after a "mass shooting" at a supermarket in Buffalo, New York, in the United States, police said.

Another three were injured in the attack at the Tops Friendly Market, Buffalo Police Commissioner Joseph Gramaglia said,

The gunmen was in police custody and being questioned by the FBI. The agency said they were investigating a "hate crime" and " racially motivated extremism."

The gunman entered the supermarket with a rifle and opened fire, said a law enforcement officer speaking on condition of anonymity to the AP news agency.

Investigators believe the man may have been live-streaming the shooting. Witnesses reported he was wearing military-style clothing and body armor.

A crowd gathered as police investigated after shots were fired at a Tops Friendly Markets shop Deutsche Welle

White House Press Secretary Karine Jean-Pierre said President Joe Biden is receiving regular updates on the shooting and its aftermath.

"The president has been briefed by his Homeland Security advisor on the horrific shooting in Buffalo, NY, this afternoon. He will continue to receive updates throughout the evening and tomorrow as further information develops," she said

New York Governor Kathy Hochul said on Twitter that she was monitoring the shooting.

The supermarket is in a predominately Black neighborhood and the surrounding area is primarily residential.

Biden decries 'act of domestic terrorism'

White House Press Secretary Karine Jean-Pierre said President Joe Biden had been briefed on the "horrific shooting" and its aftermath.

In a statement, Biden said investigators were still looking into the motivation for the shooting, but "we don't need anything else to state a clear moral truth: A racially motivated hate crime is abhorrent to the very fabric of this nation."

"Any act of domestic terrorism, including an act perpetrated in the name of a repugnant white nationalist ideology, is antithetical to everything we stand for in America," he said.

New York Governor Kathy Hochul said on Twitter that she will "ensure law enforcement has what they need to prosecute the shooter to the fullest extent."

Saturday's shooting came after recent racially motivated mass killings in the US.

Several initiatives to stem gun violence have failed to pass in Congress despite recurring mass-casualty shootings across the country.

In 2020, the US recorded 19,350 firearm homicides, up nearly 35% compared to 2019, according to the Centers for Disease Control and Prevention (CDC).