The bodies of two people missing at the site of a powerful explosion at a chocolate factory in eastern Pennsylvania have been recovered, taking the death toll to seven.

The explosion happened on Friday afternoon at the RM Palmer Co plant in West Reading, about 60 miles north west of Philadelphia.

Mayor Samantha Kaag confirmed the discovery of the last two bodies, adding that none of the victims will be named until officials are certain that all families have been contacted.

She said: “Please understand that this is a devastating loss, but we are truly grateful to bring closure to the families involved in the upcoming days.”

One woman was pulled alive from the rubble early on Saturday (Ben Hasty/Reading Eagle via AP)

Three buildings around the site will be condemned as a precaution, she said.

“This does not mean they are slated for demolition or uninhabitable,” she said.

“Simply that there will still be work happening around them as we proceed and they will need to be looked at further by structural engineers.”

One woman was pulled alive from the rubble early on Saturday after being located by a search dog.

Reading Hospital said it received 10 patients and transferred two to other facilities, while two others were admitted in good and fair condition respectively and the others had been discharged.

A statement from RM Palmer said everyone at the company was “devastated” and it was reaching out to employees and their families through first responders and disaster recovery organisations because its communication systems were down.

Governor Josh Shapiro vowed support from the state when he visited the scene on Saturday.

Fire investigators are continuing to examine the scene to try to determine the cause of the blast.