MIDLOTHIAN - A thin layer of sleet and snow covered area roads and snarled morning traffic Wednesday as Midlothian police and ambulance crews worked three auto accidents in the space of an hour.

The most serious accident occurred about 8:30 a.m. on the westbound lane of U.S. Highway 287 Bypass when a 2002 Ford Mustang allegedly spun out of control on the overpass of U.S. Highway 67 and was hit by an 18-wheeler. The accident pinned the driver of the Mustang in her car.

“I came on the bridge and suddenly that car was spinning and going round and round,” said Bud Sugar, of Strawn, the driver of the Freightliner tractor-trailer carrying a load of clay. “I just held on and hit the brakes as soon as she hit me.”

Midlothian police officer Steve Egan was unable to give details of the accident, saying the incident was "under investigation."

The 18-wheeler hit the driver’s side of the Mustang and pinned it against the guardrail. The driver was transported by ground ambulance to Methodist Hospital in Mansfield.

“We had to pop the passenger-side door off to get her out,” said Midlothian firefighter Jake Godfrey. “The injuries were pretty minor considering the damage to the car. It could have been a lot worse.”

The wreck jack-knifed the 18-wheeler and brought westbound traffic to a complete halt. Traffic backed up for more than a mile and most of it was rerouted through town.

At the same time an accident in the eastbound lane of U.S. Highway 287 Bypass, also at the U.S. Highway 67 overpass, slowed the morning commute in that lane.

The bridges that climb the chalk escarpment in Midlothian are elevated and are some of the first areas to freeze up when cold weather calls.

Midlothian saw temperatures around freezing Tuesday night. Large flakes fell briefly as kids headed off to school Wednesday morning and this was followed by sleet and then a light rain. The heaviest accumulations appeared to fall in a line from Cleburne to Waxahachie.

A third accident was reported in the 200 block of U.S. Highway 287 Frontage Road in front of Wal-Mart.

That accident was quickly cleared by authorities and wreckers.