A multiple-vehicle wreck Friday night in the northbound lanes of I-85 in Gwinnett County resulted in several injuries and snarled traffic for nearly seven miles, authorities said.

An adult and a child were airlifted from the accident scene after they were freed from separate cars, Gwinnett Fire Department spokesman Capt. Tommy Rutledge said. Both were in critical condition.

No deaths were reported, Rutledge said.

The six-vehicle pile-up, which involved at least one tractor-trailer, happened around 6:30 p.m. during rush hour traffic between Pleasant Hill Road and Ga. 316.

All northbound lanes were blocked until about 8:40 p.m., according to the Georgia Department of Transportation’s Web site.

Three other people sustained minor to moderate injuries and were taken to area hospitals, authorities said. A fourth injured motorist was treated at the scene and released.