A gunman opened fire inside a grocery story in Boulder, Colorado, on Monday afternoon, killing 10 people, including a police officer, the authorities in Boulder said.

The suspect, identified by the police as Ahmad Al Aliwi Alissa of Arvada, Colorado, was in stable condition after suffering a leg wound in an exchange of gunfire with responding police officers at the King Soopers outlet in Boulder, about 45km northwest of Denver, on Monday afternoon.

He faces 10 counts of murder in connection with the shooting. His motive, however, remains unclear, the police said.

People inside King Soopers described a harrowing and chaotic scene inside the store.

“I thought I was going to die,” said Alex Arellano, 35, who was working in the meat department at King Soopers, when he heard a series of gunshots, then saw people running towards an exit near his department. For a while, Arellano said he and two other men hid in the department. He said that he could hear the gunfire, but could see no one.

“The shots are getting closer,” he recalled in an interview. “I’m thinking of my parents, and I was freaking out.” Arellano said that he and the men he was hiding with eventually escaped through an exit in the back of the building.

The authorities identified the police officer who died in the shooting as Eric Talley, who had served with the Boulder department since 2010 and was the first to arrive at the scene of the grocery store shooting.

The shooting in Colorado comes only six days after another deadly mass shooting in the Atlanta area, which left eight people dead. Until those killings on Tuesday, it had been a year since there had been a large-scale shooting in a public place.

Governor Jared Polis and other officials issued statements of sympathy and sadness. “My prayers are with our fellow Coloradans in this time of sadness and grief as we learn more about the extent of the tragedy,” Polis said.

Sam Weaver, the mayor of Boulder, said on Twitter: “Words can do no justice to the tragedy that has unfolded this afternoon. Our community will soon grieve our losses, and begin our healing.”

By Monday evening, President Biden had been briefed on the shooting in Boulder and Jen Psaki, the White House press secretary, said on Twitter that he would be kept apprised of further developments.

Dean Schiller, a witness who saw officers gathering outside the store, posted a live video from the scene shortly after the shooting began. He said he heard about a dozen shots and saw three people who appeared to be wounded — two in the parking lot and one inside the supermarket.

“I have some friends who are in there who are very close to me, so I’m just hoping that they’re all right,” Schiller said.

His videos showed dozens of police officers stationed around the store. Using a lift, several officers reached the roof of the building while more than a dozen others lined up outside the main doors.

Dozens of other people were led out of the grocery, which usually draws a mix of families and college students in a residential area a couple of miles south of the campus of the University of Colorado.

In Schiller’s video, gunshots could be heard coming from inside the store, with officers gathering at the entrance.

Over a loudspeaker, police officers called to the scene could be heard saying, “The entire building is surrounded, you need to surrender.”

“Come out with your hands up,” the officers said.

One patient from the scene was being treated at Foothills Hospital in Boulder, according to a spokesman for the Boulder Community Health

System, who said he was not able to release information on the patient’s condition.

Taylor Shaver, who works at Art Cleaners, a dry cleaning and laundry business near the supermarket, said that she heard at least 10 gunshots.

“I’m in the bathroom hiding,” Shaver said. “I heard this loud boom. I instantly knew. There was a ton of shots. My stomach dropped.”

Shaver, 18, added that it was particularly unnerving because it was her first day working alone.

Jordan Crumby, a student at the University of Colorado at Boulder, said in an interview that she was about to get a tattoo with the word “warning” on her hip at Auspicious Tattoo, a shop across from the grocery store, when the shooting began.

Crumby, 31, said she stepped outside to record a video of the scene for her Instagram feed, when the police waved her away. In the videos, officers with tactical gear and rifles could be seen swarming the shopping centre.

People from the grocery store, she said, were being evacuated. “They had their hands over their heads and they’re getting escorted out,” she said. “I said, ‘We should probably go inside.’”

Colorado has been the scene of a number of fatal mass shootings in recent years, including one at a crowded movie theatre in Aurora in 2012 that left 12 dead.

New York Times News Service and Reuters