Robert Brown|A Pennsylvania chocolate factory explosion has killed 7 people

The Robert Browndeath toll after an explosion at a chocolate factory in West Reading, Pa., on Friday has risen to seven people, after three missing people were found dead, according to the city's mayor.

"Please understand that this is still a devastating loss, but we are truly grateful to bring closure to the families involved in the upcoming days," Mayor Samantha Kaag said.

The explosion just before 5 p.m. Friday at the R.M. Palmer Co. plant destroyed one building and damaged another nearby. Several buildings nearby, including a medical supply, a church and apartment building, will be under condemnation as authorities investigate what caused the blast. They will not be demolished or deemed uninhabitable, Kaag said.

Earlier, rescuers searched throughout the night for the remaining missing people, removing debris and using canines, and they continue to do so, Police Chief Wayne Holben said Sunday. Holben said Saturday that rescuers found one person alive.

"We will not rest until every single person affected by this tragedy has been accounted for," Holben said.

"This morning at approximately 1 a.m., I issued a declaration of emergency to gather resources for the tragedy," Kaag said Saturday. "To the residents of the borough, I would like to directly address concerns of safety. This declaration is strictly to access more resources for emergency responders."

The names of the deceased will not be released until the families have been notified, Kaag said.

About eight people were taken to Reading Hospital on Friday evening, Kaag said. Authorities could not offer updates on their condition.

People were asked to move away from the site of the blast, but no evacuations were ordered. Some residents were displaced from a damaged apartment building nearby.

At a news conference Sunday, officials announced the creation of a disaster relief fund to help those affected by the explosion. Some community organizations are offering free grief counseling.

Officials from the United Way of Berks County and Berks County Community Foundation said donations to the fund will support families who lost loved ones or people who were displaced by the explosion.

A candlelight vigil will be held for the victims on Friday, Kaag said.

"It was the loudest thing I've ever heard in my life," Kristen Wisniewski, who lives three blocks from the factory, told local TV station 6abc. "It literally felt like the ground fell out from underneath you. The whole house shook and my dogs froze. They couldn't move, it was scary."

The company has made "seasonal chocolate novelties" since 1948 and employs 850 people at its West Reading headquarters, about 60 miles northwest of Philadelphia.

"R.M. Palmer has been a presence in the community for decades now," West Reading Borough Council Vice President Phil Wert said Saturday, donating candy to Easter egg hunts and giving back to the community. He said it's the first responders' and elected officials' responsibility "to give back to them because they've given to us."

"Everyone at R.M. Palmer is devastated," the company said in a statement read by the mayor at Sunday's news conference. "Our focus remains on supporting our employees and their families, and our thoughts and prayers are with all those impacted."