Exposure to carbon monoxide has led at least five people to seek for treatment at New Hampshire hospitals Saturday after a malfunction at a propane production plant, say officials. The issue at the Liberty Utilities plant had occurred at 9 a.m., upon which fire authorities, as well as staff of Liberty Utility, had started conducting door-to-door evaluation of its customers.

The company said that the issue affected propane and air mixtures, which lead to a gas with "high BTU content" entering the distribution system, according to Reuters.

"The high BTU mixture in the Keene pipeline system can potentially produce carbon monoxide at the gas appliance/burner tip in a home or business," Liberty described in a statement.

Fire officials of Keene, N.H. received multiple calls and have also asked multiple neighboring communities for back-up assistance. Firefighters had to respond to more than 104 calls related to the leaks. The staff and crew finished checking 60 percent of the of their target search at around 9 p.m., which consisted of 1,250 customers. No issues had cropped up yet, officials say.

The American Red Cross also opened a warming center at the Keene Recreation center on Washington Street from 6:30 p.m. until 11 p.m. Saturday, CBS Boston reported.

"Anybody that smells gas and is a customer of Liberty Utilities or the city gas system should call 911 if they haven't already. Anybody who is a customer of Liberty Utilities, again the city underground system, should be opening windows in their homes and ventilating their homes," Keene Fire Chief Mark Howard said at a press briefing. "Unless you have CO monitors within your home you could have CO readings within your business or with your home."

He also said that the main dangers that people face is suffocation. A six-alarm emergency had been struck in the city of Keene when the issue happened, which has brought in 33 engine companies, three ladder companies and 11 ambulances into the city, according to the New Hampshire Union Leader.