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A truck driver fatally stabbed three people and wounded another at a Tennessee travel center Tuesday before he was killed by a sheriff's deputy, authorities said.

A motive for the rampage outside Knoxville is not known, said Leslie Earhart, a public information officer for the Tennessee Bureau of Investigation.

Idris Abdus-Salaam, 33, a truck driver from Durham, North Carolina, was shot and killed after attacking four people at the Pilot Travel Center, the TBI said.

Officials said that when Knox County sheriff's deputies arrived at the travel center about 7 a.m., they found one person who had been stabbed outside the store and a man armed with a knife in the parking lot.

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"Officers confronted the individual who refused to drop the weapon," the TBI said. "At some point during the encounter, one of the officers fired shots, striking the man. He was pronounced dead at the scene."

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The three people who were killed were employees at the travel center, and the fourth victim was a customer, Pilot CEO Jimmy Haslam said in a statement provided to NBC affiliate WBIR of Knoxville.

Authorities identifies those who were killed as Joyce Whaley, 57; Patricia Denise Nibbe, 51; and Nettie R. Spencer, 41. The identity and condition of the customer, who was hospitalized, were not released.

Kermit McPeek, pastor of The Crossing Church in Kodak, told WBIR that Whaley was "one of the most caring people I've ever met." She leaves behind her husband, two daughters and two grandchildren, he said.

Joshua Moore, senior pastor of Grace Community Church in New Market, told WBIR that Nibbe "was one of the most giving people, willing to help in an instant in any situation."

The TBI is also investigating the circumstances of the deputy shooting.

"I'm asking that the public join me in praying for all of those who lost a loved one today, for the victim that remains in the hospital, for my Deputies and all of the First Responders," Knox County Sheriff Tom Spangler said in a statement.

A phone number for Abdus-Salaam or anyone who may be associated with him could not immediately be found Tuesday night.