At least 13 people have been hospitalized after dangerous fumes at the New Rochelle YMCA filled the Upstate New York pool house, causing those inside to evacuate.

Authorities were called to the location at Weyman Avenue and Bayard Street at around 7:14 a.m. with a report of chemical exposure causing respiratory distress, according to local law enforcement.

Michelle Arezou Ross, a reporter for PIX11 News, was told that a lifeguard requested a maintenance worker add chlorine to the chemical mix to clean the pool, but accidentally added hydrochloric acid.

“People were overcome and we had to help some of them get out of the building,” said New Rochelle Fire Chief Andrew Sandor. He added that along with breathing problems, some victims had suffered skin injuries such as rashes and burns as well.

“When these two chemicals are mixed,” said the fire chief, “it’s called off-gassing, caused a reaction, and makes the whole atmosphere around unsafe. At this stage it appears to have been just an accident, nothing malicious.”

The products involved reportedly included Super8 and Scale Kleen, which when mixed can emit a gas that “made a number of people sick.”

Of the 13 hospitalized, only one victim was reported to be in critical condition. Six ambulances arrived to escort the injured to a medical facility.

Witnesses at the scene told CBS News New York that “it felt like their lungs were on fire” as people made a “mad dash to escape the building.”

CBS News reporter Tony Aiello reported that the “mass casualty” scene was treated with oxygen, as EMT units “toweled people down to remove chemical residue that could irritate the skin.”

According to a photojournalist on the scene for PIX11 News, emergency responders had to get decontaminated every time they went in and out of the building.

“Couldn’t breath anymore,” said New Rochelle YMCA swimmer Nikolai Pamukoff. “Obvious mistake in mixing chemicals. Next thing you know, it’s just an act of desperation to get out of the pool. Everyone is coughing, desperately trying to get out any which way. Just an awful scene.”

Another New Rochelle YMCA goer, Adam Holmes, said that he was working out on a stationary bike at the gym when “multiple people came running out, choking, coughing.”

A similar incident occurred just last week in St. Louis, Mo., when fire fighters reported to a hydrochloric acid spill at the aeronautics center after it was accidentally mixed with water causing yellowish-brown hydro fluorine gas clouds to form. Only two firefighters were injured, but later released after treatment.

According to the Environmental Protection Agency, hydrochloric acid, which is primarily used as a cleaning agent, is “corrosive to the eyes, skin, and mucous membranes.”

“Acute (short-term) inhalation exposure may cause eye, nose, and respiratory tract irritation and inflammation and pulmonary edema in humans,” the EPA warned.

But as a cleaning chloride, the hydrochloric acid was presumably mixed up with chlorine when the maintenance worker was advised to add more cleaning solution to the pool. An investigation is still ongoing.

The immediate area outside of the building “appears to be unaffected at this time,” according to fire fighter Joseph Ruggiero, who blocked off the road so that none of the possible gaseous fumes could affect passerby’s at the Home Depot next door.

New Rochelle firefighters and first responders said that the New Rochelle YMCA is “contained for the time being.”

The building was later tested and cleared for dangerous fumes after hours of ventilation, but the New Rochelle YMCA will be closed for the remainder of the day. The YMCA staff officials hope to be able to reopen tomorrow.