(CNN) Police arrived "to a very chaotic scene, with victims and witnesses running everywhere" at a FedEx Ground facility near Indianapolis' main airport late Thursday night, where a former employee shot and killed eight people and wounded several others, an Indianapolis police official told CNN.
Deputy Chief Craig McCartt on Friday afternoon identified the gunman as 19-year-old Brandon Hole, who was last employed by FedEx in 2020.
Hole was found dead of a gunshot wound that appeared to be self-inflicted, McCartt said.
In March 2020, Hole's mother told law enforcement that he might attempt "suicide by cop," the FBI's Indianapolis office said in a statement.
Special Agent in Charge Paul Keenan said Hole was placed on an immediate mental health temporary hold by the Indianapolis Metropolitan Police Department. He also said a shotgun was seized at Hole's residence.
"Based on items observed in the suspect's bedroom at that time, he was interviewed by the FBI in April 2020," the statement said. "No Racially Motivated Violent Extremism (RMVE) ideology was identified during the course of the assessment and no criminal violation was found. The shotgun was not returned to the suspect."
McCartt told reporters that Indianapolis police found Hole's name in two past incident reports. The deputy chief didn't have information about the first report. The details he described from a 2020 report align with the FBI statement.
Investigators are trying to determine motive and were searching what they believe is the suspected gunman's home, Keenan told reporters late Friday morning.
When asked what brought the suspected gunman to the FedEx facility Thursday around 11 p.m., McCartt said: "I wish we could answer that."
On Friday evening, Indianapolis police released the names of the eight deceased victims. They are: Matthew R. Alexander, 32; Samaria Blackwell, 19; Amarjeet Johal, 66; Jaswinder Kaur, 64; Jaswinder Singh, 68; Amarjit Sekhon, 48; Karli Smith, 19; and John Weisert, 74.
A statement by IMPD said the next of kin has been notified by the Marion County Coroner's Office. The cause of death will be determined after autopsies are complete, according to the statement.
IMPD said the names of those injured are not being released.
The mass shooting is the country's deadliest since 10 people were killed March 22 at a grocery store in Boulder, Colorado.
Thursday night's killings began when a gunman "got out of his car, and pretty quickly started some random shooting outside the facility," McCartt said.
The gunman then "went inside and did not get very far into the facility at all," while shooting others there, McCartt told CNN earlier Friday.
Laveda Chester told CNN's "OutFront with Erin Burnett" that she was arriving for her overnight shift when she heard one pop and thought it might be a car accident. She said she looked around and didn't see one. But then she saw the gunman running toward the building with a rifle in his hand.
She waited until he went in so she could drive away without drawing the gunman's attention. She went to another parking lot and called police. She said she then tried to warn other arriving workers that there was a shooting going on. Some stopped and some drove past her.
Two employees inside the building at the time heard as many as 10 gunshots, they told CNN affiliate WISH. The men left the building and watched as about 30 police cars responded, they said.
"Thank God for being here because I thought I was going to get shot," one of them, Jeremiah Miller, told WISH.
Investigators have heard the shooting lasted "just a couple minutes -- that it did not last very long," McCartt said.
"My understanding is, by the time that officers entered ... the situation was over -- that the suspect took his life very shortly before officers entered the facility," McCartt told reporters.
There were at least 100 people in the facility when the shooting began, he said. Many were on their dinner break or changing shifts.
Four people were found dead outside and four others, not counting the shooter, were dead inside, McCartt said.
The incident marks at least the 45th mass shooting in the United States since the Atlanta-area spa shootings on March 16. CNN considers an incident to be a mass shooting if four or more people, excluding the gunman, are wounded or killed by gunfire.
President Joe Biden ordered flags at federal facilities to be lowered to half-staff and urged Congress to act on firearm legislation, calling gun violence an "epidemic."
McCartt said four survivors were taken to a hospital with gunshot wounds and a fifth person sought treatment in another county for a gunshot wound. Two people were treated at the scene, he said.
The gunman had at least one weapon, which investigators believe was a rifle, McCartt told reporters.
Police early Friday were trying to make sense of the crime scene while relatives of FedEx employees gathered at a nearby hotel, which officials offered as a place where they could await news, reunite with the workers and meet with police chaplains.
"Many of the employees did not have cell phones on them in the facility," and so many survivors were not immediately able to contact their families, McCartt told CNN.
Several people tearfully embraced as they reunited Friday morning at the hotel, video from CNN affiliate WISH showed.
When asked Friday morning whether witnesses indicated that FedEx or security personnel had any indication that something like Friday's shooting would happen, McCartt said no.
"We're still working with FedEx security for anything that might have been an indication this was going to happen right now," McCartt said at the Friday morning news conference.
FedEx worker Timothy Boillat and his coworker heard what they thought initially were "two loud metal clangs" when the shooting started, he told CNN affiliate WRTV.
"They didn't sound like gunshots at first ... Then, we heard three more shots, and then my buddy ... saw someone running out of the building." Boillat said.
"And then more shots went off. Somebody went behind their car to the trunk and got another gun," Boillat said, without saying whether that person was the shooter.
"And then I saw one body on the floor," Boillat told WRTV.
Police are asking anyone who was at the scene and may have left for safety or for medical treatment to contact them to provide information on the shooting.
Indianapolis Mayor Joe Hogsett said the process of healing will be impacted in part by what conversations the nation has about cycles of violence "driven by readily accessible guns."
"We must guard against resignation or even despair -- the assumption that this is simply how it must be and that we might as well get used to it. We need the courage that compels courageous acts that push past weariness," Hogsett said.
FedEx released a statement saying it was "deeply shocked and saddened by the loss of our team members."
"Our most heartfelt sympathies are with all those affected by this senseless act of violence. The safety of our team members is our top priority, and we are fully cooperating with investigating authorities," FedEx said.
Indiana Gov. Eric Holcomb said Friday is "another heartbreaking day and I'm shaken by the mass shooting at the FedEx Ground facility in Indianapolis."
"In times like this, words like justice and sorrow fall short in response for those senselessly taken. Our thoughts are with the families, friends, coworkers and all those affected by this terrible situation," Holcomb said.
Flags will be lowered to half-staff from Friday until sunset Tuesday "in remembrance of those we've lost," Holcomb said.
"Nothing we learn can heal the wounds of those who escaped with their lives, but who will now ... endure the memories of this horrific crime," Hogsett said.
US Rep. Andre Carson, whose district includes Indianapolis, tweeted that he was heartbroken by the mass shooting.
"I am communicating with local authorities to get all details of the attack and my office stands ready to help everyone affected any way we can," he said.
Correction: A previous version of this article misstated the names of Amarjit Sekhon and Karli Smith based on information provided by the Indianapolis Metropolitan Police Department.