Louisville police have released the dramatic 911 calls from Monday's mass shooting inside a bank.

One woman who called 911 said about eight or nine people have been shot. She said she was hiding in a closet in the first-floor conference room.

She told the dispatcher she knew the shooter, who worked with her.

Loud gunshots are heard booming in the background as the employee recounted what was happening.

The dispatcher told the woman to stay quiet and stay where she was. Whispering, she told the dispatcher there was a lot of blood.

The mother of the suspected gunman, 25-year-old Connor Sturgeon, called 911 to say her son's roommate called her and was concerned.

"He apparently left a note," she said.

"He's never hurt anyone, he's a really good kid," Sturgeon's mother told the dispatcher. "I don't know where he would've gotten a gun."

"I know he doesn't own any guns!" she told the dispatcher.

Sturgeon, who was killed by police at the scene, bought the AR-15 used in the attack legally on April 4 in Louisville, according to police.

Nickolas Wilt, the rookie Louisville police officer shot in the head while responding to Monday's shooting at Old National Bank, is "slowly improving," city authorities told ABC News Wednesday morning.

Wilt remains in critical condition, however. He was the only victim still listed in critical condition.

-ABC News' Will McDuffie

The family of the suspected gunman, 25-year-old Connor Sturgeon, issued a statement Monday night expressing their sorrow, also saying "there were never any warning signs or indications he was capable of this shocking act."

"No words can express our sorrow, anguish, and horror at the unthinkable harm our son Connor inflicted on innocent people, their families, and the entire Louisville community," the Sturgeon family said. "We mourn their loss and that of our son, Connor. We pray for everyone traumatized by his senseless acts of violence and are deeply grateful for the bravery and heroism of the Louisville Metropolitan Police Department."

"While Connor, like many of his contemporaries, had mental health challenges which we, as a family, were actively addressing, there were never any warning signs or indications he was capable of this shocking act," the family said. "While we have many unanswered questions, we will continue to cooperate fully with law enforcement officials and do all we can to aid everyone in understanding why and how this happened."

-ABC News' Alondra Valle

Louisville Deputy Chief Paul Humphrey provided a timeline of the police response to Monday's shooting while sharing body camera footage from the responding officers:

--8:38 a.m.: Officers dispatched.

--8:41 a.m.: Officers Nickolas Wilt and Cory Galloway pull up to an entrance to the bank. Gunshots are immediately fired in their direction, forcing them to back up the car.

--8:42 a.m.: They exit the vehicle.

--8:44 a.m.: Wilt is struck and officers return fire. When Wilt is struck, Galloway is heard yelling, "He’s down! Get the officer!”

--8:45 a.m.: After a short barrage of gunfire, officers make entry to the bank and confirm the suspect is down.

-ABC News' Will McDuffie

Officers arrived at the Old National Bank within three minutes of being dispatched and found the suspect still firing, Louisville police said.

Officers exchanged gunfire with the suspect who died at the scene, police said. It's not yet clear if the suspect's wounds were self-inflicted, police said.

Four victims were killed and eight people are injured, police said.

At least two officers were shot during the exchange of gunfire, police said, including one who is undergoing surgery.

It appears the suspect was a previous or current employee, police said.

"This is awful. I have a very close friend that didn't make it today. And I have another close friend who didn't, either, and one who is at the hospital that I hope is gonna make it through," Kentucky Gov. Andy Beshear said at a news conference.

"The safety of Old National Bank employees and everyone we serve in our banking center locations is paramount,” Jim Ryan, the CEO of Old National Bank, said in a statement. “As we await more details, we are deploying employee assistance support and keeping everyone affected by this tragedy in our thoughts and prayers."