Police have just started what they believe 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’s what we know so far:
According to Maris Herold, Boulder Police Chief, the first 911 calls reporting shots came in on Monday at around 2:30 p.m. local time (4:30 p.m. ET), and Officer Eric Talley was the first officer to arrive on the scene.
At 2:40 PM, officers radioed in on a gunfight, according to audio from scanner traffic.
Scanner traffic shows that police continued to report that they were shot at multiple rounds until at least 3:21 PM
“He’s armed with a rifle, our agents fired back and fired back – we don’t know where he is in the store,” said an officer.
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, the police were seen moving on the roof of the store. The reason for the relocations was unclear, but a witness speaking to CNN-affiliated KCNC said his family members were evacuated through the roof at the store.
Who are the victims?
Talley, 51, was killed on the spot, police chief Herold said. Talley, a father of seven, had joined the Boulder Police Department in 2010, she said.
Officials did not disclose the identities of the other victims and said they should first notify family members.
Who is the suspect?
A suspect is in custody, Herold said, but authorities have not shared his identity or any information about the type of weapon being used or any possible motive.
As events unfolded, KMGH’s helicopter registered a shirtless man being taken from the supermarket. The man had what looked like blood on his arm and right leg, and his hands seemed shackled behind him as two officers led him away. The man was taken away by ambulance.
It was unclear whether the man was involved in the shop shooting.
A senior law enforcement source told CNN that the weapon used in the shooting was an AR-15 style rifle.
Where is the research headed now?
Police will be on the scene day and night to learn about the violence that took place in the store, officials said.
“We will be working around the clock to get this done,” Herold said, adding that such a complex investigation will take at least five days.
In the US, there have been at least six mass shootings so far this year, killing four or more.
CNN’s Steve Almasy, Paul P. Murphy, Melissa Gray, Keith Allen, Kelsie Smith, Deanna Hackney, Dianne Gallagher and Joe Sutton contributed to this report.