Emergency responders arrived about 6 a.m. Thursday at the scene of a rollover collision on northbound Interstate 5 south of Highway 516, according to the Washington State Department of Transportation.

The collision near Kent-Des Moines Road closed two right lanes on the northbound side of the freeway, with traffic initially backed up for about 5 miles, WSDOT said.

Just after 7:40 a.m., WSDOT reported that backups from the crash extended to the King-Pierce county line, with additional snarls caused by cars attempting to leave Highway 516. The backups slowed travel times from Federal Way to Seattle, Bellevue and SeaTac.

Trooper Rick Johnson said on Twitter that the accident involved a box truck and a car. The car’s driver sustained serious injuries, he said, and there was “no suspected impairment on the box truck driver.”

The car had been stopped on the shoulder when it was hit, and it was possible that the driver of the box truck had fallen asleep at the wheel, said Johnson.

In an update posted on Twitter just after 8:30 a.m., WSDOT reported that one lane of the freeway had reopened. All were open again by 9:45 a.m.