A man driving a sport utility vehicle died after triggering three accidents, which caused a massive traffic backup on southbound Interstate 15 in Salt Lake County on Friday afternoon.

The final crash happened near 8500 South, killing Sheldon Taylor, 54, of Sandy, who was behind the wheel of a small red SUV, said Utah Highway Patrol Sgt. Blaine Robbins.

The other two collisions, involving six other vehicles, happened near 5500 South and 7800 South as other motorists tried to avoid Taylor.

Taylor sped up behind other cars, then slammed on the brakes and backed off, and darted back and forth. The three collisions happened over a five-minute period, ending about 12:50 p.m.

Finally, Taylor's SUV hit a white car and the two cars became "tangled" Robbins said. They veered across the road to the right, hit a concrete barrier, then veered back left. The SUV rolled once, landing on its top and killing Taylor.

Other motorists were not seriously hurt.

Troopers were investigating why Taylor was driving so dangerously, but think he may have suffered a medical problem. Other drivers had reported his driving to police starting around 1300 South.

"He was driving really erratically, like potentially there was something else wrong there," said Robbins. He was not wearing a seat belt.

The road was closed near 8500 South for about an hour.