Police are looking into a racial motivation behind the mass shooting inside a Buffalo supermarket that left at least 10 people dead and several more injured on Saturday.

The gunman, who appeared to be in his late teens or early twenties, lived-streamed the assault as he opened fire inside the Tops Friendly Supermarket, at 1275 Jefferson Avenue, at about 2.30pm.

The suspect, filmed wearing a military uniform, has been taken into custody by the Buffalo Police Department.

The n-word could been seen written on the front gunsight of his automatic rifle.

Sources told NBC that the shooter entered the store wearing body armor and carrying two rifles.

When the shooter re-emerged from the supermarket to surrender to police, a witness told Buffalo 4 News that he put the gun up to his chin, then dropped it and removed his gloves.

He ‘took something and put it on his boots, took his vest off, got on his hands and knees and put his hands behind his back.’