PETERBOROUGH, N.H. — Two explosions tore through a ball bearing plant here Monday afternoon, sending 13 people to hospitals, including two who had critical injuries, officials said.
The blasts occurred in quick succession starting at about 3:35 p.m. at New Hampshire Ball Bearings Inc. on 175 Jaffrey Road.
Peterborough Fire & Rescue said that “it was reported that the explosion[s] could be felt at neighboring businesses up to a quarter-mile away.”
The first explosion was followed by a larger blast, said Eric Bowman, a spokesman for Peterborough Fire & Rescue.
The two critically injured victims were taken by Dartmouth-Hitchcock Advanced Response Team helicopters to Boston hospitals.
Four other people had serious injuries, officials said.
Peterborough Fire & Rescue said that authorities are investigating the cause of the explosions and that New Hampshire State Police and the US Bureau of Alcohol, Tobacco, Firearms, and Explosives are aiding the probe.
“It is not believed to be an act of terrorism,” Fire & Rescue said in its statement.
Max Shultz, assistant state fire marshal, said during an evening briefing that the blasts occurred in an area of the plant where chemicals are mixed. Fire & Rescue said in a follow-up statement that the explosions appeared to be “an industrial-related incident.”
Additional details on exactly what occurred at the facility were not available late Monday night.
“We have no new information yet, but we are very concerned about the reports that two of our employees are critically injured,” Kathy Gerrity, a company spokeswoman, wrote in an e-mail Monday night.
“First responders at the facility will be investigating the cause of the incident, as well as determining the extent of the damage to the facility,” she added. “We don’t know yet when the facility will be back in operation and won’t have an idea about that until the building has been thoroughly inspected and the premises are deemed to be safe.”
Earlier in the afternoon, she had said the explosions were triggered by an unspecified “in-house issue.”
The scene was sealed off Monday evening as rescuers and investigators worked in the bitter cold. About a dozen windows on the first floor of the plant were shattered, and part of Jaffrey Road was blocked off with caution cones and a sign that read, “Emergency scene ahead.”
Some workers were being taken away from the plant in school buses.
Liane Emond, who works at Performance Health & Fitness down the street from the plant, said that some of the facility’s workers are members of the gym and came in after the blasts and described what happened.
“They were shaken up,” said Emond. “It’s a crazy time of day for something like that to happen.”
Emond said that the explosions were not heard inside the gym, noting that there is a large wooded area that cuts the gym off from the plant that may have muffled the sound. She said the blasts occurred around a shift change at the plant.
“Some people were already out, and some people were just leaving,” said Emond.
One woman, who is an employee at the plant and a gym member, was so shaken afterward that she declined to take part in her scheduled group meeting, said Emond. The woman was on the floor of the explosions, Emond said.
Governor Maggie Hassan said in a statement that her “thoughts and prayers go out to those injured in today’s explosion, to their families and loved ones, and to the entire Peterborough area where New Hampshire Ball Bearings is such an important member of the community. While we are still gathering details about the explosion, we are very encouraged to hear that all employees have been accounted for.
“The state has activated our Emergency Operations Center in order to better coordinate state resources, and we stand ready to provide any assistance needed to local first responders.”
The company says on its website that it was founded in 1946 in Peterborough and now operates three manufacturing facilities in the United States, employing more than 1,500 workers. Minebea, a global manufacturing corporation, bought the company in 1985, according to the website.
The plant employs 700 people in a town of about 6,400 residents, the Associated Press reported.
The plant on Jaffrey Road has been the subject of at least two safety complaints in the last decade, according to records posted on the website of the US Occupational Safety & Health Administration.
Globe correspondent Jacqueline Tempera contributed to this report.