A gunman killed at least 10 people including a police officer at a grocery store in the US state of Colorado on March 22, police said.
Witnesses at the King Soopers supermarket in Boulder County, 50km northwest of the state capital Denver, said they initially heard multiple loud bangs outside the shop.
Police chief Maris Herold said 10 people were killed, including officer Eric Talley, 51, who was first on the scene.
Live-streamed video earlier showed a white middle-aged man – shirtless and seemingly covered in blood – detained by police and led from the supermarket.
A suspect is being held in custody and was the only person suffering “serious injuries at this point”, said police commander Kerry Yamaguchi, without confirming that the man in the video was the suspect or giving any possible motive.
Dozens of armoured vehicles, ambulances and armed personnel including FBI agents and SWAT teams were deployed to the scene.
“Police officers’ actions fell nothing short of being heroic,” said Herold, adding that the “very complex investigation” would take at least five days to complete.
“Our hearts are broken over this senseless act of violence,” said King Soopers spokeswoman Kelli McGannon.