What to Know Emergency crews responded to a reported mass casualty incident at the Market Basket in Rowley, Massachusetts, on Thursday afternoon

Police said the incident was the result of an unknown gas leak, which has since been contained

Nine people were taken to local hospitals, but their condition was not immediately known

Nine people were hospitalized and an entire strip mall evacuated after a refrigerant leaked from an ice machine at a Market Basket store in Rowley, Massachusetts, Thursday afternoon.

The incident brought out a large number of emergency response vehicles after police were called to the supermarket on Newburyport Turnpike around 3 p.m. Rowley police said they were responding to a mass casualty incident; the Rowley Fire Department also responded.

Around 3:30 p.m., police said there was a contained gas leak at the Market Basket store and that police, fire and EMS were at the scene evaluating patients.

Rowley Fire Chief James Broderick said officials have identified a potential refrigerant leak in an ice machine at the store that might have caused the problem. Market Basket later confirmed the ice machine refrigerant leak.

"They were having a hard time breathing and had a metal taste in their mouth," Broderick said of the affected employees and customers. "It looks like vapor filled the store."

He said the incident was being treated as a Tier 1 hazmat situation. The state fire marshal's office said it sent a hazmat team to the scene, but police said that was only done as a precaution.

Aerial footage from NBC10 Boston's Sky Ranger helicopter showed numerous fire trucks and ambulances in the store's parking lot. People could be seen sitting or standing in grassy areas next to the parking lot.

The exact number of people affected shifted throughout the response to the leak.

Broderick said nine people were taken to local hospitals and another 25 were evaluated on scene for respiratory issues, though he had earlier said eight were. Police and fire officials initially told reporters that 10 people were hospitalized and more than 50 evaluated.

Four patients were sent to Anna Jacques Hospital in nearby Newburyport and four others to Beverly Hospital, Broderick said. Their conditions were not immediately known; all of them are expected to survive.

Broderick said those who were hospitalized were believed to be a mix of employees and customers.

National Grid said it was aware of the gas leak. A representative said it was informed that the leak was not a natural gas leak and the utility has not been asked to cut gas to the surrounding area.

Market Basket said the store was evacuated and closed, reopening Friday.

"We are glad to report that the issue now has been resolved and after receiving the all clear from the authorities, we will reopen Friday for normal business hours starting as usual at 7 a.m.," a store executive said in a statement Thursday night. "We are grateful for the swift response of fire and emergency personnel, as well as the prompt actions taken by our store associates."

Police and fire officials said the entire strip mall where the store is located has also been evacuated and "closed indefinitely."

No further information was immediately available. The cause of the leak remains under investigation by the Rowley Fire Department.