WEST READING, Pennsylvania (AP) — An explosion at a chocolate factory in Pennsylvania on Friday killed two people and left five people missing, authorities said. One person was pulled alive from the rubble overnight.

Rescue crews using dogs and imaging equipment continued to search through the rubble Saturday — hours after the blast that erupted just before 5:00 pm Friday at the RM Palmer Co plant in the borough of West Reading, about 60 miles (96 kilometres) northwest of Philadelphia.

West Reading officials said Saturday they could confirm only two fatalities. The Pennsylvania Emergency Management Agency had earlier said there were five fatalities, citing county emergency management officials, but after an update from the county also indicated that two had died and five were missing.

Chief of Police Wayne Holben said the rescue of one person from the rubble “provides hope that others still may be found.” Rescue workers were continuing a thorough search using specialised equipment and techniques. Officials said dogs and imaging equipment were being used to look for signs of life during the careful removal of debris.

Holben said the blast destroyed one building and damaged a neighbouring building. The cause remains under investigation, he said.

“It’s pretty levelled,” 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.”

Reading Hospital said Saturday afternoon it had received 10 patients, of which one was transferred to Lehigh Valley Hospital and another to Penn State Health St. Joseph Medical Center. Two were admitted to Reading Hospital in good and fair condition, respectively, and the others had been discharged, officials said.

A UGI Utilities spokesperson said crews were brought in after damage from the blast led to the release of gas that was helping to feed the fire.

“We did not receive any calls regarding a gas leak or gas order prior to the incident. But we are cooperating with the investigation and part of that will be to check all our facilities in the vicinity,” UGI spokesperson Joseph Swope said Saturday.

RM Palmer said in a statement late Saturday that everyone at the company was “devastated by the tragic events” and “focused on supporting our employees and their families.”

“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, expressing gratitude to the “extraordinary efforts” of first responders and the support of the Reading community, “which has been home to our business for more than 70 years.”

RM Palmer said it was anxious to get in touch with its employees and their families. But its email, phones and other communication systems were down, and it was relying on first responders and disaster recovery organisations to provide information to affected families. The company said it would be “providing additional information and making contact with employees, impacted families, and the community as soon as possible.”

Kaag said people were asked to move back about a block in each direction, but no evacuations were ordered. She had issued an emergency declaration only to allow more resources for first responders. Borough manager Dean Murray said some residents were displaced from the damaged apartment building.

Governor Josh Shapiro, who visited the site Saturday along with the emergency management agency director, vowed “any and all commonwealth resources needed to support ongoing recovery efforts –- in addition to the extensive assets that have already been deployed.”

A team of structural engineers and K-9s from a state urban search and rescue task force had been assisting since last night, and additional personnel arrived Saturday, he said. A state police fire marshal was also assisting in the investigation, he said.

Philip Wert, vice president of the West Reading council, said the building had been constructed in the late 1950s or early 1960s, and officials had to “access our archive to pull the blueprints last night, in order to get a better layout of the building and the mechanicals and the utilities, where things are.”

“The silver lining in all this is someone was found alive, someone was found alive that was in rubble, not knowing whether they were going to live or die, and fortunately we found that person and they’ve got a second chance, and hopefully fingers crossed we’re going to find more,” he said.

Frank Gonzalez stood on a hill overlooking the blast site, watching the rubble being cleared. He said his sister, Diana Cedeno, was working at the plant at the time of the blast and was among the missing.

“It’s not good. It’s just stressful waiting, not knowing,” he said, expressing frustration at what he perceived as a lack of communication from authorities about the search. “We keep reaching out, bugging, keeping her name alive just in case she is in there and says her name.”

He said his sister has two adult children, including a son who is deployed overseas. She has a side job decorating for parties and has also been studying for ministry at her church, he said.

Gonzalez said his son and nephew had also worked at the plant, but that his son had quite a few months ago “because he said he didn’t like the smell of the gas that was in there.” His son and nephew had complained about the smell to plant supervisors, who told them, ”‘It’s all right. We got it. It’s being handled. Don’t worry about it,’” he said.

Frank DeJesus said his stepdaughter, Arelis Rivera Santiago, a Palmer employee, was working in the building next door at the time of the blast. The ceiling caved, and she had to crawl under machinery to make it out, he said. DeJesus said he rushed to the scene to find her “shaking and crying hysterically,” and she was still too shaken to speak about what had happened.

Plant employees, including his stepdaughter, had complained about smelling gas throughout the day Friday, DeJesus said.

“Everyone complained about smelling gas, and they kept making them work,” he said. “The supervisors told them it was nothing. It was being taken care of.”

A message was sent earlier to RM Palmer seeking comment about the blast.

Doug Olexy was home from work and checking email when the blast shook his house, rattling windows and making the walls vibrate.

“It sounded like a bomb went off,” he recalled Saturday. “I mean, all of our houses shook. I’ve never heard as loud of an explosion in my life.”

He and his neighbours ran out onto the street immediately afterward and were met by thick black smoke. At first, Olexy thought it was a train derailment because there are tracks nearby. Then he learned it was the Palmer plant, which he called a West Reading institution.

“Everybody knows Palmer chocolate,” he said.

RM Palmer’s website says it has been making chocolate novelties since 1948 and now has 850 employees at its West Reading headquarters. Its Facebook page includes entries earlier this month advertising Easter treats such as chocolate bunnies and “the newest milk chocolate hollow” in its “bunny family” as one with jelly beans inside. The company is by no means the region’s best-known chocolate manufacturer, however, with Hershey less than an hour to the west.