At least 425 firefighters were working to gain control of the fast-moving fire, which has destroyed one structure and is 30 percent contained, said Jody Hagemann, spokeswoman for the county fire department.
The design featured a wooden frame on top of a concrete-slab foundation, with an exterior covered in gray asbestos shingles. (Steel was in short supply.) The structure violated the Cambridge fire code, but it was granted an exemption because of its temporary status.