The South Dakota Highway Patrol is investigating a serious rollover accident near Harrisburg. The crash happened east of Harrisburg, near the South Dakota-Iowa border, shortly before 3 a.m. Tuesday.

Authorities say four men in a car were heading west on 272nd Street, when the driver overshot a T-shaped intersection. The car then nose-dived off the road, and rolled front-first onto its top.

One of the men was thrown from the vehicle, and all four were taken to hospitals, two of them by air.

Speed and alcohol are likely factors in the crash, according to the Highway Patrol. None of the men were believed to be wearing seat belts.