(NECN: Alysha Palumbo - Nashua, N.H.) - An explosion rocked this Nashua, New Hampshire industrial plant Saturday morning, seriously injuring several workers inside. "Immediately we did have two people who were injured, possibly seriously," said Deputy Chief Michael O'Brien with the Nashua Fire Department, "They were given immediate medical attention and extricated from the building." Deputy Fire Chief Michael O'Brien says although the two unidentified employees of Worthen Industries were conscious and talking to first responders on the scene, by the time they were rushed to local hospitals, their conditions had worsened. "At that point, due to the severity of their injuries they were life-flighted by two separate helicopters to Boston Hospitals where they are now currently being treated," said O'Brien. An off-site contractor and two other employees were also injured in the industrial accident and taken to local hospitals. O'Brien says their injuries are less severe. "The accident is under investigation by the Nashua Fire Marshal's Office and also with the Nashua Police Department," said O'Brien. The Deputy Fire Chief wouldn't elaborate on the cause of this explosion, but he did say the Worthen Industries plant here in Nashua, NH does house some potentially dangerous chemicals. O'Brien said, "It appears that the company is a company that takes chemicals with a chemical process and they make solvents and glues and other different types of products." Deputy Chief O'Brien says Worthen Industries has cooperated fully with the investigation. "The company right now is shut down during this particular investigation and after the investigation is complete I'm sure they'll come back to some clean up and operations," said the Deputy Chief. O'Brien says the explosion did not cause any structural damage and did not damage the infrastructure of the utilities in the area.