COBB COUNTY, Ga. -- Officials at Six Flags and radio station Q-100 apologized Thursday for a stunt that caused a massive traffic jam and left thousands of people angry.

The promise of free admission to Six Flags backed up traffic during the morning rush hour Thursday on I-20 and surrounding roads.

Carloads of people hoping to get into the park for free began lining up at the Six Flags parking lot before 5:00 a.m. The "Ditch Work" promotion offered free admission to the amusement park between 6 and 9 a.m.

Traffic began backing up in both directions on I-20 before 5:30 a.m. Frustrated drivers let passengers out of their vehicles to walk along the Interstate to the park.

SEE WHAT COMMUTERS HAVE TO SAY: Stuck In Six Flags Traffic?

Those pedestrians, many of them children, wanted to get in line at the park entrance. But Six Flags workers turned them away, telling them admission was limited to people in vehicles. That caused even more problems when those walkers began trekking back to their vehicles, wandering on the interstate searching for their rides.

VIDEO: Chaos, Joy At Six Flags

There were reports of fights near the park's front gates.

Once Six Flags officials opened the parking lots at 5:30, they filled up quickly. Park officials decided to end the free admission promotion at 5:55 a.m., turning away thousands of people.

A spokesperson from Zoo Atlanta tells us they’ve been swamped with families all day and they’re thanking Six Flags.

They believe so many people were turned away from the amusement park they looked for an alternative way to spend the day.

SLIDESHOW CENTRAL: Massive Lines At Zoo Atlanta