Lance Cpl. Joseph Robinson of South Carolina Highway Patrol said the driver of the vehicle involved, Daniel Johnson, was northbound on Beech Island Avenue approximately 12 miles south of North Augusta, when he came up on the five cyclists, who also were northbound on Beech Island Avenue.
Inattentive and unaware of the cyclists' presence, Johnson's Dodge struck the group of them from behind, Robinson said.
Transported to Medical College of Georgia Hospital by ambulance in "very serious" condition, Robinson said, was Matthew Burke, 37, of Martinez.
Also injured in the wreck and transported by ambulance to area hospitals were the other cyclists: Laura Farmer, 47, of Augusta; Scott Moore, 39, of Augusta; Judith Speck, 42, of North Augusta, and Hugh Ray, 42, of Martinez.
All the cyclists were wearing helmets and reflective gear, Robinson said.
Johnson was not injured and alcohol does not appear to be a factor in the crash, according to the highway patrol.
The incident remains under investigation and no charges have been filed yet, but charges might be filed by the end of the week, Robinson said.