Emergency HAZMAT crews will have to test the soil for contamination in a small town in southeastern Colorado.

Crews are returning Thursday to ensure no chemicals got into the groundwater after an ammonia spill Wednesday morning in Walsh. The spill forced dozens of residents to be evacuated for several hours.

Riley Frazee, a representative for the Division of Emergency Management, says the chemical involved is considered an extremely hazardous substance by the EPA. It is called anhydrous ammonia, and is used as a fertilizer.

It can cause death if inhaled in large quantities, but luckily everyone in the area evacuated immediately. There were no injuries.

Frazee says the tank was being pulled behind a pickup truck for delivery to a farm south of Walsh. The front axle of the trailer broke, and the tank slammed into the pavement. Two valves on the front of the tank broke, allowing the chemical to leak out and form a hazardous cloud.

One neighbor saw the accident happen.

"I looked back and saw the anhydrous ammonia tank fall...saw the smoke go up, so I called 911 for help," Margaret Collins told 11 News.

Crews were able to get the ammonia tank secured and the valves plugged. The tank was moved to a safe location.

Reports have indicated the tank had an estimated capacity of between 500 and 1,000 gallons.

About 700 people live in Walsh.

The leak was centered near where South Illinois Street merges with County Road 44.