The pharmaceutical plant where a powerful blast killed a Massachusetts worker is set to move into the cleanup phase Friday. Firefighters paused work overnight at the Newburyport plant, where a hazardous materials call went to seven alarms Thursday. The search for the person who died was initially hampered by concern about the plant’s structural integrity. Crews were expected to stop working overnight and return Friday morning to continue removing chemicals. U.S. Sen. Edward Mark says the explosion is the facility’s third accident since 2020 and he says the company needs to be held accountable.