A motorist died Friday when his car struck a median and rolled over on Route 24 in Brockton, authorities said.

Brian Charles Jr., 22, of Brockton, was driving south about 5:20 a.m. when his 2012 Volkswagen Passat swerved into the median. He was thrown from the car and pronounced dead at the scene, police said. He was driving alone.

The crash took place near Exit 17, police said. All three southbound lanes of Route 24 were closed for about 3½ hours, police said. The cause of the accident remained under investigation Friday.

John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.