CNN  — 

A gunman who killed a woman and wounded at least 14 other people at a western Tennessee Kroger before apparently killing himself this week was a third-party vendor for the store, police said Friday.

UK Thang, 29, was the man who shot 10 employees and five customers Thursday afternoon at the Kroger in Collierville, some 30 miles southeast of downtown Memphis, police said.

Investigators are still trying to determine a motive, Collierville Police Chief Dale Lane said at a news conference Friday morning.

“We all want to know the ‘why.’ But today, less than 24 hours (in), we’re not ready to tell you that,” Lane said.

The gunman opened fire around 1:30 p.m., sending numerous people running for cover in freezers, offices and elsewhere, police said.

The woman who died was Olivia King, Lane said Friday. She was a customer, according to Kroger.

“Our family is devastated by this senseless act of violence,” King’s family said in an earlier written statement to CNN affiliate WHBQ. The asked for prayers “for all families and friends affected by the events today, as well as for God’s mercy on the shooter and his family.”

Three shooting victims were in critical condition Friday at Regional One Health Medical Center in Memphis, said Dr. Andrew Kerwin, the hospital’s trauma and critical care director.

Some of the injured have been released from hospitals, Lane said. The names of the survivors were not immediately released.

The shooting was over minutes after police received a 911 call, and investigators believe the gunman fatally shot himself “as we were pulling up to the scene,” Lane said.

Police and Kroger officials have not said what service the gunman had performed as a third-party vendor.

The incident was one of at least 517 mass shootings in the United States so far this year, according to the Gun Violence Archive. CNN and the GVA identify a mass shooting as a shooting that injured or killed four or more people, not including the shooter.

Wes King, Olivia’s son, said his mom was shot in the chest. “This type of crime needs to stop being glossed over and sanitized. No one deserves this,” he wrote on his Facebook page.

Police said earlier the gunman had killed one person and shot and wounded 13 others, and a separate person checked into a hospital with an anxiety attack.

Olivia King, right, with son Mark King.

People hid in freezers

Witnesses and police described scenes of chaos and desperation at the store.

Jason Lusk told CNN he was leaving a tool store beside Kroger when he saw people running out of the store screaming there was a shooter.

When he didn’t see anybody initially, Lusk said he began walking toward his car. “That’s when I heard about 10 to 15 shots fired. Sounded like they were directly over my head. Very close proximity. Sounded to me to be a high-powered semi-automatic rifle,” he said.