Authorities have reportedly identified the suspect in a shooting at an Indianapolis FedEx facility as 19-year-old Brandon Scott Hole of Indiana.
According to The Associated Press, two law enforcement officials briefed on the matter provided the identity of the gunman.
Investigators are searching a home in Indianapolis associated with Hole and have seized evidence, including desktop computers and other electronic media, the officials said. The officials could not discuss the matter publicly and spoke to the AP on condition of anonymity.
The gunman shot dead eight people at a FedEx centre in Indianapolis before taking his own life, police said on Friday in the latest mass shooting to grip the US after a relative lull during the pandemic.
The massacre in Indiana's state capital, which occurred near the city's airport, also left five people in hospital including one with critical injuries, police said.
"Last night and into the morning in Indianapolis, yet again families had to wait to hear word about the fate of their loved ones," President Joe Biden said in a statement.
"What a cruel wait and fate that has become too normal and happens every day somewhere in our nation."
The shooting only lasted a couple of minutes and was already over by the time police arrived, Craig McCartt, the Indianapolis police department's deputy chief, told a news briefing.
Witnesses described a chaotic scene as the gunman opened fire in the parking lot before entering the centre and continuing to fire.
Officers found the gunman dead inside the building of an apparent self-inflicted gunshot wound, along with four victims. The other four victims were outside.
FedEx said people who worked for the company were among the eight dead.
Sgt John Perrine, an Indiana State police spokesman, told relatives of FedEx employees to gather at a local Holiday Inn to await word on loved ones.
Some said employees are not allowed to have their phones with them while working shifts at the site, making it difficult to contact them, WTHR-TV reported.
“I see a man come out with a rifle in his hand and he starts firing and he starts yelling stuff that I could not understand,” witness Levi Miller told WTHR-TV.
“What I ended up doing was ducking down to make sure he did not see me because I thought he would see me and he would shoot me.”
Family members of Fedex Employees who are attempting to come to the scene please go to the Holiday Inn Express at 8555 Stansted Drive, Indianapolis #FedEx @IMPDnews pic.twitter.com/RVd6CZPtcJ
— Sgt. John Perrine (@ISPIndianapolis) April 16, 2021
Everyday gun violence in the US has continued unabated during the pandemic, but the rate of headline-grabbing mass shootings had slowed until recently.
At the end of last month, four people, including a child, were shot dead in an office building in southern California.
On March 22, 10 people were killed in a shooting at a grocery shop in Boulder, Colorado.
That came less than a week after a man shot and killed eight people, including six women of Asian descent, at spas in Atlanta, Georgia.
The issue of gun regulation in the US is politically fraught and the nation has for years been unable to control gun violence.
About 40,000 people in the US die each year from shootings and gun incidents. More than half the deaths are suicides.
Mr Biden last week announced six executive measures he said would help to stem the gun violence crisis.
But his attempt to slow the violence was immediately attacked by Republicans, with the party's senior leader in the House of Representatives, Kevin McCarthy, using the phrase "unconstitutional overreach".
"Too many Americans are dying every single day from gun violence. It stains our character and pierces the very soul of our nation," Mr Biden said in Friday's statement.
