Gwinnett County investigators do not know what prompted a man to get out of his vehicle Thursday morning and walk into oncoming traffic on I-85.

Ronald Brown, 56, of Buford, was hit by a Toyota Rav 4 near Boggs Road when he entered the third southbound lane, according to police. He was dead at the scene.

The incident shut down all lanes of I-85 South for three hours and caused major delays for the entirety of the Thursday morning rush.

PHOTO GALLERY: Deadly pedestrian crash on I-85 in Gwinnett County

According to Gwinnett traffic investigators, Brown was struck about 4:40 a.m. after he parked his vehicle on the right shoulder just north of the Ga. 316 interchange. The driver of the Toyota, who was not identified by police, was also injured in the collision.

The Toyota’s driver was taken to a hospital and is expected to recover, police spokesman Officer J.D. Albright said in a news release.

“It is unknown why Brown entered into the roadway at the time he was struck,” he said.

There were bumper-to-bumper delays on I-85 South on Thursday morning after a pedestrian was killed near Boggs Road.

Credit: JOHN SPINK / JSPINK@AJC.COM

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Credit: JOHN SPINK / JSPINK@AJC.COM

The lanes were reopened at 7:40 a.m. after police towed the Toyota and Brown’s vehicle from the scene. Even after traffic was moving again, commutes all across the Eastside were severely impacted.

The incident remains under investigation, police said.

In other news:

President Donald Trump has arrived in metro Atlanta to launch a drive to recruit more African-American voters.