WASHINGTON: An explosion at a chocolate factory in Pennsylvania has left at least five people dead with six others missing as rescue workers search through debris for survivors, emergency services said on Saturday.

The blast occurred on Friday at the R.M. Palmer Company plant in West Reading, a town about 60 miles (97 km) northwest of Philadelphia, the Pennsylvania Emergency Management Agency (PEMA) said.

PEMA said an investigation would be conducted to determine the cause of the explosion, and that an initial incident report included reference to a gas leak.

Seven other people were transported to local hospitals with injuries, it added. PEMA did not provide details on search and rescue operations. Images on social media of the explosion’s aftermath showed a vast pile of debris and massive flames letting off large plumes of thick black smoke, in a downtown area surrounded by other buildings.

The R.M. Palmer Company was founded in 1948. It employs some 850 people and creates 500 unique chocolate and candy products, according to its website.

The company did not immediately respond to a request for comment.