Ten people at a grocery store in Buffalo, New York were killed on Saturday when a gunman opened fire, local daily The Buffalo News reported citing police officials.
Up to five bodies were found in the parking lot, as well as multiple people inside the store.
A police source told the newspaper that the shooter had a camera and was wearing body armor with a "military-grade helmet."
"Ten people were killed by a gunman dressed in body armor and armed with a high-powered rifle, while three others were wounded -- two of them critically," reported the paper, citing a police official at the scene and another source close to law enforcement.
The Buffalo Police department tweeted at 3:26 pm (1926 GMT) that officers were "on scene of a mass shooting at the Tops" grocery store, and that the "shooter is in custody."
"Police say multiple people have been struck by gunfire," the tweet added.
The police are investigating whether the shooter live-streamed the attack, the paper said, as has been alleged on social media.
"It's like walking onto a horror movie, but everything is real. It is Armageddon-like," a police official told the paper.
"I'm actively monitoring the situation with the grocery store shooting in Buffalo. We are standing with the people of Buffalo," said the senior US senator from New York state, Chuck Schumer, in a tweet.
