PHILADELPHIA—Federal officials have proposed nearly $400,000 in penalties for two companies involved in a botched building demolition that killed six people in Philadelphia.

The fines announced Thursday by the Occupational Safety and Health Administration stem from the collapse of a Salvation Army thrift shop.

OSHA says Campbell Construction and S&R Contracting committed willful and serious breaches of standard demolition practices.

The firms were knocking down a vacant structure in June when an unsupported four-story wall crashed down onto the neighboring thrift store, trapping shoppers.

Violations include failure to demolish the building from the top down and leaving an unsupported wall more than one story high.

The companies have 15 days to respond to the citations. Lawyers for the firms could not immediately be reached for comment.