A huge explosion at a chocolate factory has left two dead, with nine people still missing.

The blast, at the R.M Palmer Co. plant in Pennsylvania, sent thick smoke into the air.

Shocking video shows debris flying into the street, with the force of the explosion enough to shake the camera.

The blast, which sparked a fire, destroyed one building and damaged a number of neighbouring apartments.

The blast destroyed the R.M. Palmer Co. plant in West Reading, Pennsylvania (Picture: AP)

Thick plumes of smoke could be seen for miles (Picture: TWITTER @Based_In410 via REUTERS)

Emergency services were called to the scene at 5pm yesterday.

‘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.’

The cause of the blast in the community about 60 miles northwest of Philadelphia was under investigation.

A general view shows smoke coming out from the chocolate factory after a fire broke out (Picture: TWITTER @Based_In410 via REUTERS)

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 as to where.

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.

Liz Soto witnessed the explosion and is desperately trying to find a friend who works at the plant.

She told FOX 29: ’She went to work, she’s confirmed to have gone to work, but we don’t know anything about her.’

Ms Soto also described a ‘loud noise, like a roaring sound’ in the seconds before the explosion.

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.

Its tagline is ‘making candy fun’.

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Shocking video shows debris flying into the street, with the force of the explosion enough to shake the camera.