She was taken to the hospital in critical condition on Tuesday; she died Wednesday morning.
The suspect, Mickey Russell, 58, is the victim's estranged husband. The victim filed for divorce in April, police said. Police added the suspect lived in the Buena Vista area.
Witnesses said there was a confrontation between the two inside the building.
"I believe that there may have been a short chase inside the building and shots were fired," Denver Police commander Ron Saunier said. "Ultimately the victim was struck."
Russell was found dead minutes after the shooting. Police said he apparently died from a self-inflicted gunshot wound.
"There had been some ramblings and some thoughts of him doing this," Saunier said. "He was becoming more and more mentally unstable."
He was banned from the airport in Buena Vista based on some comments he had made, Saunier said.
Employees told Denver7 there had been recent security threats at the Alliance Center prior to the shooting.
Denver Police said it was aware of the threats, but had not found any connection with the shooter.
The Alliance Center was closed for business Wednesday, but a sign on the door said it will re-open at 7:30 a.m. Thursday.
The Alliance released the following statement on Wednesday:
At 2:42 p.m. yesterday, the first call came in to 911. The response of the Denver Police Department was immediate, and we remain grateful for their continued excellent work, as officers were onsite within minutes. The tragedy occurred on the second floor of the building, and we know it not to be a random act. We worked with police to help identify the suspect immediately.
While we continue to grieve as a community, we understand the importance of the work that takes place in this community space. The building will reopen tomorrow morning, with grief counselors onsite Thursday and Friday of this week. We feel confident that we have all appropriate security precautions in place, and we are actively working with the police to routinely assess and identify any updated measures, as we take the safety of our tenants very seriously.
There is a planned vigil to be held tomorrow, June 30, at The Alliance building at the end of the workday. It will be held in honor of Cara Russell and her family, and the Alliance community, all of whom continue to grieve.
For background on the building, The Alliance Center houses 49 separate groups, comprised of 220 individuals, making up a supporting and engaging family of organizations within the community space, which is known as Colorado’s Hub Of Sustainability. The building hosts more than 350 events each year from across the state.