Young identified those killed in the Hyundai as Wendy Melton, 39, of Reidsville, Brittanie Altman, 16, of Claxton, and Virgil Moody, 19, of Hagan, a small town near Claxton.
The two people killed in the Honda were identified as Jerry Earnest, 71, of Varnell in northwest Georgia, and Glenda Adams, 72, of Cohutta, also in northwest Georgia.
The driver of the tractor-trailer that slammed into the cars was identified as David Gibbons, 61, of Pooler.
Pooler police Chief Mark Revenew said Gibbons survived the crash with no serious injuries.
Young said Gibbons, who works for Georgia Freightways, was pulling an empty trailer to Savannah when the wreck occurred.
“It’s too early to tell, but early indications are the driver may have fallen asleep,” said Revenew, whose officers are helping the Georgia State Patrol investigate the crash.
She said charges are pending the completion of the investigation.
The deadly collision happened less than a month after an April 22 crash involving a tractor-trailer on I-16 killed five nursing students from Georgia Southern University. The earlier wreck happened less than 20 miles west of the crash Tuesday afternoon.
—The Associated Press contributed to this article.