TULSA, Oklahoma - Police said a 37-year-old man has died after a rollover crash Monday morning on Highway 75 just north of downtown Tulsa.  

The crash is located just north of 36th Street North where police say a sign for Amber Alerts and other messages is under construction.

Officers say the southbound crash shut down the inside lane of the highway in both directions while police investigate. They got the call just after 7 a.m.

Police say the car hit a concrete barrier and then rolled over.  It has led to a big backup for southbound drivers.

An officer at the scene said there were no signs of skid marks on the road, so they aren't sure what caused the crash. It appears the driver just drifted off the road, he said.

Sergeant Stephen Florea said the driver may have been distracted by something like cell phone use or may have fallen asleep. There weren't any indications of anything other than highway speeds, and it does not appear any other vehicles were involved, he said.

The roads weren't slick at the time, Florea said.

Crews are working hard to finish up the investigation and reopen the highway.