A four-car collision sent two people, including a Gwinnett County police officer, to the hospital with serious injuries Monday.

The wreck closed four northbound lanes of I-85 for hours while Gwinnett officers investigated. The crash happened on I-85 just south of Lawrenceville-Suwanee Road in unincorporated Suwanee.

Officer Todd Ramsey, 22, was in his patrol car when he struck the rear end of a Kia Sorento. He notified Gwinnett Communications he had been involved in a crash just before 5:30 p.m., spokesman Wilbert Rundles said.

Because Ramsey was hurt, he couldn’t assess the condition of the other people involved, Rundles said. Several other officers responded to the scene.

Ramsey and the woman driving the Kia Sorento — Sarah Wood, 33, of Hoschton— were taken to a hospital, Rundles said.

Ramsey is still there but has been moved out of the ICU, Rundles said. The officer is in serious condition. Wood is still hospitalized in serious condition, Rundles said.

Yosha Burnside, 21, of Lawrenceville, was driving a 2007 Honda Elantra that was involved in the wreck. She was checked at the scene for complaints of injuries but was not taken to a hospital.

James Carolus, 31, who was driving a 2012 Chevy Silverado that was involved in the crash, said he was not hurt and was eventually allowed to drive his car away from the scene.

Rudles said the other three cars were taken to Gwinnett police headquarters for analysis.

The cause of the crash is under investigation.

In other news:

It happened on Cherokee Valley Drive.