Here's what we know about the mass shooting in Colorado that left 10 dead

I just looked at my son and I told him, We have three seconds. Stay low and don't look and just move fast. 10 people killed during a shooting at the King's Soopers Monday afternoon. One of the victims, Boulder, Colorado, Police Officer Eric Tally. We know of 10 fatalities at the scene, including one of our Boulder PD officers by the name of Eric Tally, who's been on the Boulder Police Department since 2010. The terrifying scene captured by this witness video. As the event unfolded, he went in the store down here. Oh, my God. Guys, we got people down inside. King Soopers, look. Yeah. Holy mm. Others describing how shoppers helped each other get to safety. The employees in the back of the house didn't know what was going on, so we told them there was a shooter and they told us where the exit was. Police say they have a suspect in custody and the investigation into the shooting will take at least five days. My heart goes out to the victims of this incident

Ten people, including a Boulder police officer, were killed Monday when a gunman attacked a King Soopers grocery store in Colorado.Police are just beginning what they say could be at least five days of investigation, and many questions about the mass shooting and the motivation behind the attack are still unclear. Here is what we know so far:What happened?According to Boulder Police Chief Maris Herold, the first 911 calls reporting shots fired came in around 2:30 p.m. local time (4:30 p.m. ET) on Monday, and Officer Eric Talley was the first officer to arrive at the scene.At 2:40 p.m, officers radioed that they were in a gunfight, according to audio from scanner traffic.Nine minutes later, Boulder police tweeted that there was an "Active Shooter at the King Soopers on Table Mesa. AVOID THE AREA."Scanner traffic shows police continued to report that they were being fired at with multiple rounds through at least 3:21 p.m."He's armed with a rifle, our officers shot back and returned fire — we do not know where he is in the store," one officer said.Ambulances and multiple law enforcement agencies responded to the store, which is part of a large shopping center with a two-story strip mall next door.At one point, police were seen moving on the roof of the store. The reason for the movements was unclear, but one witness who spoke to KCNC said his relatives in the store were evacuated through the roof.Who are the victims?Talley, 51, was killed at the scene, police chief Herold said. Talley, a father of seven, had joined the Boulder police force in 2010, she said.On Tuesday, authorities also identified nine victims who were killed in the shooting.The victims include Denny Stong, 20; Neven Stanisic, 23; Rikki Olds, 25; Tralona Bartkowiak, 49; Suzanne Fountain, 59; Teri Leiker, 51; Kevin Mahoney, 61; Lynn Murray, 62; and Jody Waters, 65.Who is the suspect?Ahmad Al Aliwi Alissa, 21, of Arvada, Colorado faces 10 counts of murder in the first degree, Herold said Tuesday.Authorities have not shared any information on the type of weapon used or any possible motive.As events unfolded, KMGH's helicopter recorded a shirtless man being taken from the supermarket. The man had what appeared to be blood on his arm and right leg and his hands appeared to be cuffed behind him as two officers escorted him away. The man was taken away in an ambulance.It was unclear whether the man was involved in the shooting inside the store.One senior law enforcement source told CNN the weapon used in the shooting was an AR-15-style rifle.Where does the investigation go next?Police will be on the scene Tuesday and night to learn more about the violence that took place at the store, officials said."We will work around the clock to get this accomplished," Herold said, adding that such a complex investigation will take at least five days to complete.The killings come less than a week after three spa shootings in Atlanta, in which eight people were killed.So far this year, there have been at least six mass killings in the U.S., defined as events in which four or more people are killed.

BOULDER, Colo. —

Ten people, including a Boulder police officer, were killed Monday when a gunman attacked a King Soopers grocery store in Colorado.

Police are just beginning what they say could be at least five days of investigation, and many questions about the mass shooting and the motivation behind the attack are still unclear. Here is what we know so far:

What happened?

According to Boulder Police Chief Maris Herold, the first 911 calls reporting shots fired came in around 2:30 p.m. local time (4:30 p.m. ET) on Monday, and Officer Eric Talley was the first officer to arrive at the scene.

At 2:40 p.m, officers radioed that they were in a gunfight, according to audio from scanner traffic.

Nine minutes later, Boulder police that there was an "Active Shooter at the King Soopers on Table Mesa. AVOID THE AREA."

Scanner traffic shows police continued to report that they were being fired at with multiple rounds through at least 3:21 p.m.

"He's armed with a rifle, our officers shot back and returned fire — we do not know where he is in the store," one officer said.

Ambulances and multiple law enforcement agencies responded to the store, which is part of a large shopping center with a two-story strip mall next door.

At one point, police were seen moving on the roof of the store. The reason for the movements was unclear, but one witness who spoke to KCNC said his relatives in the store were evacuated through the roof.

Who are the victims?

Talley, 51, was killed at the scene, police chief Herold said. Talley, a father of seven, had joined the Boulder police force in 2010, she said.

On Tuesday, authorities also identified nine victims who were killed in the shooting.

The victims include Denny Stong, 20; Neven Stanisic, 23; Rikki Olds, 25; Tralona Bartkowiak, 49; Suzanne Fountain, 59; Teri Leiker, 51; Kevin Mahoney, 61; Lynn Murray, 62; and Jody Waters, 65.

Who is the suspect?

Ahmad Al Aliwi Alissa, 21, of Arvada, Colorado faces 10 counts of murder in the first degree, Herold said Tuesday.

Authorities have not shared any information on the type of weapon used or any possible motive.

As events unfolded, KMGH's helicopter recorded a shirtless man being taken from the supermarket. The man had what appeared to be blood on his arm and right leg and his hands appeared to be cuffed behind him as two officers escorted him away. The man was taken away in an ambulance.

It was unclear whether the man was involved in the shooting inside the store.

One senior law enforcement source told CNN the weapon used in the shooting was an AR-15-style rifle.

Where does the investigation go next?

Police will be on the scene Tuesday and night to learn more about the violence that took place at the store, officials said.

"We will work around the clock to get this accomplished," Herold said, adding that such a complex investigation will take at least five days to complete.

The killings come less than a week after three spa shootings in Atlanta, in which eight people were killed.

So far this year, there have been at least six mass killings in the U.S., defined as events in which four or more people are killed.

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