WEST READING, Pa. (WHTM) — An explosion at a chocolate factory in Pennsylvania on Friday killed three people and left four people missing, authorities said. One person was pulled alive from the rubble overnight.

Rescue crews using dogs and imaging equipment continued to search through the rubble Saturday — hours after the blast that erupted just before 5 p.m. Friday at the R.M. Palmer Co. plant in the borough of West Reading, about 60 miles northwest of Philadelphia.

West Reading Borough Chief of Police Wayne Holben said the death toll rose on Saturday with the discovery of a third body at the site. The Berks County Medical Examiner and Coroner on Saturday night also confirmed three fatalities.

Borough Fire Chief Chad Moyer said four people remained missing as emergency personnel continue searching for victims and state and local fire investigators examine the scene to determine a cause.

“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. “However, please be assured that our primary goal is accounting for all missing individuals and reuniting them with their loved ones.”

Holben earlier said the rescue of one person from the rubble “provides hope that others still may be found.” Rescue workers were continuing a thorough search using specialized equipment and techniques. Officials said dogs and imaging equipment were being used to look for signs of life during the careful removal of debris.

R.M. Palmer Company, the chocolate company that owns the factory that was destroyed in the explosion, as well as The Hershey Company released statements.

In the statement, R.M. Palmer sai the company was “devastated by the tragic events at one of our West Reading facilities and we are focused on supporting our employees and their families. We have lost close friends and colleagues, and our thoughts and prayers are with the families and friends of all who have been impacted.”

In a Facebook post, the Hershey Company said, “Our deepest condolences are with the families and loved ones, partners and fellow candy makers at the R.M. Palmer Company. We are heartbroken for them as well as the community of West Reading. Thank you to the first responders and their dedicated work, and know that we are here to offer comfort and support to all.”

The Associated Press contributed to this report.