(CNN) -- A loft office collapsed at a Colorado Salvation Army thrift store, sending debris onto people below and launching a search for someone who may be missing, authorities said Friday.
The second-story loft collapsed around 3 p.m., when 22 people were in the thrift store and warehouse complex in Grand Junction, Fire Department spokesman Mike Page told CNN.
One person may be missing, Page said.
The search was taking several hours because of the large quantity of rubble that was being removed by hand, Page said. About 60 percent of the area had been searched by Friday night, and police dogs were assisting.
Rescuers have tried thermal imaging at the facility on Ute Avenue, Page said. Teams drilled a hole into the wall on the opposite side of the building to continue the search operation.
Michele Mahoney, who works at a nearby business, said she heard a loud noise around 3:15 p.m. and came outside to discover a chaotic scene.
CNN's Greg Morrison contributed to this report.