KNOXVILLE, Tenn. - Three people were killed and a fourth was wounded in a stabbing at a truck stop in Tennessee Tuesday morning that ended when the assailant was fatally shot by a responding sheriff's deputy, authorities confirmed.

The attack was reported to 911 shortly before 7 a.m. at a Pilot Travel Center off Interstate 40. Investigators have yet to establish a motive, said Leslie Earhart, a spokeswoman for the Tennessee Bureau of Investigation.

“At this point, that's what we're trying to determine,” she said.

All three women killed in the attack were Pilot employees, Pilot CEO Jimmy Haslam confirmed in a statement. They are Joyce Whaley, 57; Patricia Denise Nibbe, 51; and Nettie R. Spencer, 41. They were pronounced dead at the scene.

A fourth victim, a female customer, remains hospitalized. Her condition was not immediately available.

"Today is a difficult day for the Pilot Company family," Haslam said in the statement. "We are devastated to confirm the loss of three team members and the injury of a guest after an act of violence at our Strawberry Plains, Tennessee, location this morning.

"It is with heavy hearts that we extend our deepest sympathy to the families and loved ones of the victims. We are providing support and counseling to the families and our team. We are working closely with local authorities.

"Please keep these families in your thoughts and prayers."

The attacker has been identified by the TBI as Idris Abdus-Salaam, a 33-year-old truck driver from Durham, North Carolina.

Earhart said it was not immediately clear whether the attacker knew any of his victims.

Knox County Sheriff's Office deputies arrived within two minutes of the reported attack to find stabbing victims both inside and outside the store.

“It’s a very large scene,” Earhart said.

The deputies confronted Abdus-Salaam, who was armed with a knife, in the parking lot. One of the officers fatally shot him after he refused to drop his weapon, Earhart said.

No deputies were hurt during the encounter.

Dozens of Knox County Sheriff's and Knoxville Police Department officers converged on the scene moments later, along with a TBI mobile command center.

Haslam also arrived and could be seen conferring with Knox County Sheriff Tom Spangler and other authorities outside the travel center.

The assailant's body was later shrouded by a white tent, amid evidence markers that flagged several shell casings, in the roadway at Strawberry Plains Pike and Region Lane, just beyond the edge of the Pilot property.

"Our prayers and condolences are with the victims and the families of the victims and everyone involved," Knox County Mayor Glenn Jacobs told Knox News. "Also, I just want to thank the heroes who stopped that. It was a horrific, horrific event."

Contributing: Travis Dorman, Knoxville News-Sentinel

Follow Hayes Hickman on Twitter: @KNS_Hayes