Beavercreek police said they received calls about a possible wreck just after 12:30 a.m.

The crash happened as the driver, 19-year-old David Allbery, left Route 35 Eastbound and headed onto the ramp that leads to Interstate 675 north or south.

SLIDESHOW: Beavercreek Rollover Crash

Sgt. Jeff Fiorita said, "Upon arrival we found a vehicle on its top, the driver was outside the vehicle with serious injuries."

Investigators said they believe Allbery lost control, skidded off the left side of the ramp, plowed through some grass and hit a guardrail and bounced back.

Police said they are not sure if the car overturned before or after the impact with the guardrail. They said Allbery was ejected during the rollover.

Paramedics took Allbery to Miami Valley Hospital, where he is listed in critical condition.

Police shut down the ramp from 35 East to I-675 for several hours while technical crash investigators looked for any available clues that might explain why Allbery lost control.

Investigators are checking several possibilities including high speeds, potential alcohol involvement and mechanical or medical problems. They have not made any official determination so far.