A day of waiting ended without answers Monday as searchers were unable to find two women missing after Sunday’s deadly explosion at the New River Castings plant.

Officials also continued to search for the cause of the blast, with union officials charging that Intermet Corp., the Troy, Mich.-based owner of the automobile parts maker, ignored complaints about gas leaks.

Search dogs indicated that Debbie Sheppard, 37, of Riner, and Karen Anderson Hamilton, 35, of Plum Creek probably were buried beneath rubble that officials said would take days to clear.

Radford Fire Chief Lee Simpkins said the workers apparently are under a “four-story building collapsed into two stories,” but said he still hoped they were alive. Commercial Steel Erection, a Madison Heights company, is being called in to help remove tons of debris during an around-the-clock recovery effort, Simpkins said.