A 50-year-old man was killed Friday afternoon in a crash on the Main Street Bridge.

The crash, which happened just after 4 p.m., completely closed the bridge for about two hours.

Police said Jonathan Kirkland Jr. was driving a white Jeep Cherokee southbound and lost control for unknown reasons, crossing into the northbound lanes and striking a northbound black Ford Expedition nearly head-on. The driver of the northbound SUV was taken to a hospital in serious condition.

TRAFFIC MAP: Monitor conditions on major arteries

According to the Jacksonville Sheriff's Office, speed or alcohol do not appear to be factors in the crash. Kirkland was not wearing a seat belt.

With thousands of people headed downtown for the season's first preseason Jaguars game, the crash created a massive traffic jam backup. Police held a 5:30 p.m. news conference to announce alternate routes, directing people to the Hart and Acosta bridges.

JSO Traffic Homicide detectives are investigating the crash.