An explosion at a chocolate factory in Pennsylvania Friday killed two people and left nine people missing, authorities said.

Several other people were injured by the explosion at the R.M. Palmer Co. plant, said West Reading Borough Police Department Chief of Police Wayne Holben, who did not confirm the exact number of injured.

The explosion just before 5 p.m. sent a plume of black smoke into the air, destroying one building and damaging a neighboring building that included apartments.

“It’s pretty leveled,” West Reading Borough Mayor Samantha Kaag said of the explosion site. “The building in the front, with the church and the apartments, the explosion was so big that it moved that building four feet forward."

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The cause of the blast in the community about 60 miles (96 kilometers) northwest of Philadelphia was under investigation, Holden told reporters.

Eight people were taken to Reading Hospital Friday evening, Tower Health spokeswoman Jessica Bezler said.

Two people were admitted in fair condition and five were being treated and would be released, she said in an email. One patient was transferred to another facility, but Bezler provided no further details.

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Kaag said people were asked to move back about a block in each direction from the site of the explosion but no evacuations were ordered.

Dean Murray, the borough manager of West Reading Borough, said some residents were displaced from the damaged apartment building.

Kagg said borough officials were not in immediate contact with officials from R.M. Palmer, which Murray described as “a staple of the borough.”

The company's website says it has been making “chocolate novelties” since 1948 and now has 850 employees at its West Reading headquarters.