At around 2:30 p.m. on Mar. 23, 2021, law enforcement officials said that a 21-year-old man from a Denver suburb began shooting using an assault-style rifle. Employees and shoppers ran for cover after hearing gunshots, some of them escaping through an employee stock area, and a loading dock at the back of the store.

About six hours after the shooting, the Boulder police chief, Maris Herold, announced that 10 people had been killed, including a police officer.

Police later confirmed that the shooting suspect, identified as 21-year-old Ahmad Al Aliwi Alissa, carried a Ruger AR-556 pistol — equipped to function similarly to a rifle, with a longer-than-normal barrel — and a 9 mm semi-automatic handgun. He kept firing the Ruger as he moved toward the store’s eastern entrance.

Ryan Borowski had just grabbed a bag of Boulder Canyon chips from the end of an aisle when he heard the sound of a gunshot.

“The first thought was a hope that it wasn’t,” he said. “The second shot shattered that hope. By the third shot, we were running.”

The employees that were working in the stockroom were unaware of what was happening at the front of the store. Suddenly they saw an influx of people fleeing, including Borowski, who was still carrying his chips and a 12-pack of Cherry Cokes, which he eventually dropped.

“We were telling them, ‘Gun, gun, gun! Shooter! Run for your life!’” Borowski exclaimed. He escaped out a back loading dock, along with several other people.

Calls from the grocery store flooded 911 lines. Just before 2:33 p.m., the first alert was heard across police radios. Sirens wailed outside the store as police rushed to the scene. The first officers arrived within two minutes.

A female officer appeared to be first, followed by a male officer. Bystanders shouted at the officers informing them the shooter was inside, and that they last saw him in the back of the store.

The gunman fired twice at the police. Officer Eric Talley, 51, was fatally shot in the head. He fell about 30 feet inside the east entrance.

“Officer down inside the building!” a male officer shouted on the radio.

Police and the shooter exchanged gunfire. At one point, the gunman fired at Officer Richard Steidell, moving as he pulled the trigger.

About 3 p.m., roughly 30 minutes after the first 911 calls, police officers began using a sound system to repeatedly order the suspect to surrender.

Pharmacy technician Maggie Montoya, 25, hid with another pharmacist in a small room which is used to administer the COVID-19 vaccine near the front corner of the store, told Colorado Public Radio that she heard two calls for the suspect to surrender.

Both times, Montoya said, she heard the response of the gunman, who was standing near the pharmacy: “He said, ‘I surrender, I’m naked.’”

At 3:22 p.m. SWAT teams went back into the grocery store. By this time, police were on the roof, armored trucks surrounded the building, drones circled inside and outside the store, and ambulances lined against a street near the store to transport the wounded.

After the gunman was taken into custody, police teams cautiously searched the building and evacuated those who had been in hiding.

When they reached Montoya and her coworker, the officers urged them to keep their eyes focused on their own feet as they walked out, but she still caught a glimpse of a beloved fallen coworker near the front.

Days after the attack, mourners have set flowers against the temporary chain link fence that now surrounds King Soopers and its lot. The makeshift memorial swelled as people left teddy bears, balloons, artwork, and signs.

Community members have gathered for vigils and remembrances. They’ve lit candles, sung, and embraced one another.

Prosecutors charged the shooter with 10 counts of first-degree murder and one count of attempted first-degree murder, for firing at Officer Steidell.

Officials said they had two encounters in 2018 with Mr. Alissa — one on a report of third-degree assault, a misdemeanor, and one of criminal mischief. Law enforcement officials said he was known to the F.B.I. because he had ties to someone the bureau was investigating.

The lives of all those who were lost are in our prayers and those who loved each one of them dearly. With no one sure what will happen to the suspect due to his lawyer asking for him to be evaluated for a mental illness many are dealing with the grief that has swept the community.