Fire crews work to free a woman who became trapped in her car after it rolled over on Memorial Drive. (CBC)

A woman is in serious but stable condition after a noon-hour rollover on Memorial Drive east.

It happened just east of Barlow Trail around 11:30 a.m.

Witnesses said the car lost control and rolled, hitting several structures, including a utility box, cement barricade and a light standard.

"The collision itself, it caused substantial damage to the vehicle," EMS spokesman Stuart Brideaux said. "So much so, crews upon arrival couldn’t determine how many people were in the vehicle."

The car came to rest on its side.

It took fire crews about 30 minutes to free the woman from the vehicle.

Traffic was backed up as far as the Calgary Zoo exit while crews worked to save the driver.

The woman, believed to be in her late 20s, was taken to the Foothills Hospital.