A H.E.R.O. operator was seriously injured Tuesday afternoon when he was struck by a tractor-trailer while removing road debris from I-85 in Gwinnett County, authorities said.

Troy Moore of Conyers was outside of his vehicle when he was hit at about 4 p.m. in the southbound lanes of I-85 at Old Peachtree Road, according to the Georgia Department of Transportation.

Moore was taken to Gwinnett Medical Center with non-life-threatening injuries, the DOT said. He was discharged later that day, hospital officials said.

The H.E.R.O. operator had stopped his vehicle in the second lane from the right shoulder and had gotten out to remove tire debris from the highway, according to Cpl. Jake Smith of the Gwinnett County Police Department.

A blue pickup truck had stopped in the second lane about 50 yards behind the H.E.R.O. truck, a silver pickup had stopped slightly closer in the first lane, and the H.E.R.O. driver was returning to his vehicle when a tractor-trailer came up from behind, Smith said.

The tractor-trailer hit the blue pickup, sideswiped the silver one and then struck Moore before coming to a stop.

The rig's driver told police his brakes failed, Smith said. "A (state) inspector is out here now seeing if that was the case," Smith said Tuesday evening.

The driver and a passenger in the blue truck complained of pains and minor injuries and also were taken to a hospital, Smith said. The driver of the silver truck and the tractor-trailer were not hurt.

Three lanes of I-85 were blocked immediately after the accident but were reopened by 5:20 p.m.

Gwinnett police were investigating, assisted by the Georgia State Patrol, a commercial vehicle inspector with the Georgia Department of Public Safety's Motor Carrier Compliance Division, and several other H.E.R.O. units. No charges had been filed as of early Tuesday evening.

The accident was the latest serious mishap this year in involving a H.E.R.O. truck.

In January, H.E.R.O. operator Spencer Pass of Jonesboro was killed Jan. 31 while helping a motorist on I-85 south of downtown Atlanta. He was the first H.E.R.O. operator killed on the job since the Highway Emergency Response Operator program began 15 years ago.

-- The Associated Press contributed to this article.