CUMMING — A northeastern Forsyth County supermarket has been deemed safe, though authorities are at a loss to explain what sickened several people and forced the store’s evacuation Sunday afternoon.

Four people were hospitalized and the Publix on Keith Bridge Road at Hammond’s Crossing was cleared for nearly five hours after what officials first thought was an ammonia leak.

Forsyth County Fire Capt. Jason Shivers said the department’s hazardous materials team was summoned and 24 people went through a decontamination process that included taking a shower in a mobile unit and changing into fresh clothes.

"It was a fairly localized event, specifically it affected individuals in and around the produce section," Shivers said.

The store reopened at about 7:30 p.m. Publix spokeswoman Brenda Reid said Monday afternoon it still was not clear what caused people to become sick.

"When we opened the store back up, it was determined that the air was safe in the store," said Reid, adding that she did not know whether any food had to be discarded.

The store manager could not be reached Monday, and the assistant store manager declined to comment on the matter.

Shivers said no mechanical failures were found inside the building.

Publix maintenance is looking into the situation, he said, and the store’s security department is checking surveillance footage to see if someone may have released a chemical into the air.

The incident happened at about 2:45 p.m. Sunday.

Shivers said fire and emergency medical personnel received reports of a woman complaining of vomiting and difficulty breathing.

"We were afraid at first that there could be some sort of anhydrous ammonia as part of the cooling system in the building, but our technicians arrived and performed a very thorough evaluation, and that structure is not cooled with any form of ammonia," he said.

Shivers said that other people who tried to help the woman complained of similar symptoms.

The woman and three others, whose names have not been released, were taken to Northside Hospital-Forsyth for treatment. A fifth person was treated at the scene.

A hospital spokesman said Monday the four people had been released.