(WEST READING, Pa.) — Four people are dead, three are missing and several others are injured after an explosion at a chocolate factory Friday in West Reading, Pennsylvania, police and city officials said.

A fourth dead body had been pulled from the rubble at the site of the factory, officials said Sunday. One person was found alive overnight in the rubble, officials said earlier.

Crews continue to search for survivors, but the amount of time since the incident mean “the chance of finding survivors is decreasing rapidly,” said West Reading Fire Chief Chad Moyer.

Tower Heath said earlier its hospital in West Reading received 10 patients from the explosion. Of those, two were admitted and are in good and fair condition and six have been discharged. Two others were transferred to other hospitals, it said.

West Reading Mayor Samantha Kaag issued an emergency declaration Saturday to access more resources for emergency responders on the scene.

An investigation to determine the official cause of the fire will be conducted, officials said.

“In the initial incident report from Berks County to PEMA, a reference to a gas leak was included. It is really important to note that incident reports from counties are a snapshot in time of the understanding of the incident at the time the report was made,” Ruth A. Miller, PEMA’s communications director, said in a statement.

The explosion occurred around 4:57 p.m. at the RM Palmer Company in West Reading, located about 60 miles northwest of Philadelphia. It caused destruction to one building nearby and damaged another.

Mayor Kaag, a former volunteer firefighter, called the incident “pretty scary,” adding that it was so strong it pushed a building back four feet. She said the factory building was “pretty leveled” and crews will “probably” be working through the weekend to clear the debris.

In a statement Saturday, RM Palmer said it is “devastated by the tragic events.”

“We have lost close friends and colleagues, and our thoughts and prayers are with the families and friends of all who have been impacted,” the company said. “We are sincerely grateful for the extraordinary efforts of all of the first responders and for the support of our Reading community, which has been home to our business for more than 70 years.”

The company said it will continue to coordinate with local and national agencies to assist in the recovery process. It added that it has been unable to get in touch with the families of impacted employees due to downed communication systems but “will be providing additional information and making contact with employees, impacted families, and the community as soon as possible.”

Images of the scene showed smoke and flames billowing from the factory on Friday evening.

Pennsylvania Gov. Josh Shapiro was on site Saturday surveying the damage and “to pledge our support as the community recovers,” he said.

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