Authorities were investigating two incidents Monday in which pedestrians were struck by vehicles on I-75 in metro Atlanta.

In the latest incident, a man was hit by a tractor-trailer and killed just before noon on I-75 southbound near Locust Grove Road in Henry County, Henry police Lt. P. Bratton said.

Bratton told The Atlanta Journal-Constitution that investigators have not determined why the man, later identified as 52-year-old Alan Bryan Fletcher of Locust Grove, was in the roadway.

It is unknown whether Fletcher had broken down on the interstate or had just stopped, Bratton said.

The truck driver stopped after hitting Fletcher, he said.

All southbound lanes of the interstate were blocked for about an hour while police investigated the accident.

Earlier in the day, a woman was injured when she was struck by a car while standing on the Downtown Connector.

According to the Georgia State Patrol, the unidentified woman was standing in the second lane from the right on I-75/85 southbound near Fulton Street when she was hit around 10:30 a.m.

Several vehicles swerved to miss the woman, but she was eventually hit by a Kia Optima.

The woman was unconscious when taken to Grady Memorial Hospital, but the extent of her injuries was not immediately known.

—Angel K. Brooks contributed to this report.