An explosion has been reported at a Newburyport, Massachusetts, pharmaceutical manufacturing plant. When the explosion and subsequent fire occurred, there were five workers in the building. NBC 10 Boston is reporting that four workers were taken to the hospital while one remains missing. In a press release, Acting Chief Stephen Bradbury III of the Newburyport Fire Department states that structural damage to the building is preventing fire and rescue teams from entering the premises and searching for the missing worker. According to CBS Boston, when firefighters arrived at the Sequens/PCI Synthesis facility, they discovered an industrial-sized vat, which had once been inside the plant, now 30 feet away in a parking lot. The Associated Press is reporting that the explosion poses no threat to local residents and their property, but employees of the surrounding industrial park have been told to stay away.