Another person was killed in the chocolate factory explosion in West Reading, Pennsylvania, last week, raising the death toll to four as of Sunday, officials confirmed. First responders are continuing to search for three more people who are still missing in the wake of the incident.

Rescue crews worked overnight to inspect the rubble at the R.M. Palmer Company and discovered the fourth victim beneath debris early on Sunday morning, said West Reading police chief Wayne Holben during a news conference on Sunday morning. The individual was pronounced dead at the scene.

“Crews are continuing their diligent effort in sifting through the debris in order to locate any additional individuals,” the police chief said, adding that crews “are fully committed to this task” and “will do everything in our power to ensure that we bring closure to all those involved.”

“I want to assure you all that we will not rest until every single person affected by this tragedy has been accounted for,” said Holben. He could not provide an update about the woman who was pulled alive from the rubble on Saturday. 

Emergency responders and heavy equipment are seen at the site of a deadly explosion at a chocolate factory in West Reading, Pennsylvania, Saturday, March 25.

Michael Rubinkam / AP

R.M. Palmer, a candy company, operates a large factory building in West Reading, where the explosion occurred on Friday night. Videos recorded at the site showed flames and thick clouds of black smoke engulfing the building and billowing hundreds of feet into the air. The death toll initially reported after the explosion was uncertain. On Saturday, Holben and West Reading Mayor Samantha Kaag said at a news conference that two people had been confirmed dead and five remained missing. 

CBS Philadelphia reported at the time that 10 people were hospitalized with injuries sustained in the incident, six of whom had already been discharged. A spokesperson for Reading Hospital told CBS News that eight patients had been admitted there.

As emergency personnel continued to search for missing people, Fire Chief Chad Moyer said on Sunday that the likelihood of finding survivors decreases as time passes, CBS Philadelphia reported.

“Due to the violence of the explosion and the amount of time that has passed, the chance of finding survivors is decreasing rapidly,” Moyer said.

R.M. Palmer acknowledged the explosion in a statement shared to its website and said the company is “devastated by tragic events that occurred Friday evening.”

“Everyone at R.M. Palmer is devastated by tragic events that occurred Friday evening at one of our West Reading facilities we are focused on supporting our employees and their families,” the statement read in part. “We have lost close friends and colleagues, and our thoughts and prayers are with the families and friends of all who have been impacted.”

The candy company, which makes seasonal chocolates for occasions like Easter, Christmas and Halloween, employs about 850 people, according to its website. The factory in West Reading has been there since the early 1960s.