A gunman open fired at a in Boulder, Colo., on Monday, March 22, killing 10 , including a police officer, according to local authorities.

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The Boulder police said that they had taken an injured suspect into custody after the . Videos showed a handcuffed man being escorted from the building by officers, shirtless and with his right leg appearing to be covered in blood.

People inside the grocery, King Soopers, described the terrifying and chaotic scene inside the store. “I thought I was going to die,” said Alex Arellano, 35, who was working in the meat department inside the King Soopers store when he heard a series of gunshots, then saw people running toward an exit.

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Boulder Police Chief Maris Herold identified the slain officer as Eric Talley who joined the Boulder department in 2010. Herold called Talley a hero and said the 51-year-old was the first officer to arrive at the scene after calls of a “possible person with a patrol rifle.” He was fatally shot by the gunman. The investigation is expected to last a minimum of five days, according to Herold.

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