Two people were killed Saturday after a wreck that shut down all northbound lanes of I-985 in Gwinnett County for more than two hours.

For unknown reasons, a southbound vehicle crossed the median and into northbound traffic, Gwinnett police spokesman R.E. Long told Channel 2 Action News. The southbound vehicle struck a northbound vehicle, he said.

The two occupants of the southbound vehicle died and the lone occupant of the northbound vehicle was taken to a hospital with unknown injuries, Long told Channel 2.

Northbound lanes of I-985 did not reopen until just after 4:30 p.m., according to the television station.

The two people killed in the wreck have not been identified pending notification of next of kin. The crash remains under investigation.