SUMMERFIELD, Fla. -- Children squirting pepper spray in a Wal-Mart store in Marion County may have caused 30 people to become violently ill and prompted the evacuation of nearly 700 customers and employees, according to Marion County officials.

A 911 call was made by a Wal-Mart manager Wednesday afternoon after he noticed many people coughing and choking in the store. The same manager also reported that a similar incident occurred Tuesday night during the call.

When emergency workers arrived, several people reported having trouble breathing and the number quickly escalated.

Eight people were transported to hospitals for evaluation and many others were treated at the scene.

After the building was evacuated, a Marion County Fire-Rescue hazmat crew entered the 185,000-square-foot building on 178th Street and South 441 to evaluate the structure.

Officials said no hazardous materials were located and technicians said the mystery substance may have dissipated when the building was ventilated.

"It is unknown what may have caused the symptoms," a Marion County Fire-Rescue press release said. However, officials suspect children may have squirted pepper spray in the store.

Emergency crews said the substance may have originated in the automotive section of the store.

The store was reopened Thursday even though a cause for the incident was unknown.

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