At least 10 killed in 'mass shooting' at Buffalo supermarket in New York

At least 10 people have been killed in a "mass shooting" at a supermarket in the New York city of Buffalo on Saturday afternoon (local time). 

Buffalo Police Department said on Twitter officers remained at the scene of the shooting and had the alleged offender in custody.

The shooting happened at the Tops Friendly Market about 5km north of downtown Buffalo, with the surrounding area primarily residential.

A man entered the supermarket shortly after 2:30 pm and fired a rifle, US outlet ABC News reported, citing a police official.

Sources told the outlet that part of the investigation will include whether there may have been white supremacist ideology associated with the shooter

The Governor of New York, Kathy Hochul, said on Twitter she is "closely monitoring the shooting at a grocery store in Buffalo" and "have offered assistance to local officials". 

Tops supermarket released a statement saying it was disturbed and appalled.

"We are shocked and deeply saddened by this senseless act of violence and our thoughts and prayers are with the victims and their families," the statement said.

"Our top priority remains the health and well-being of our associates and customers. We appreciate the quick response of local law enforcement and are providing all available resources to assist authorities in the ongoing investigation."