Chicago Fire Department crews rescued two women and a dog trapped in the rubble of an apartment building that "pancaked" after an apparent explosion in the city's Washington Park neighborhood Sunday night. What neighbors described as a loud explosion preceded the collapse of a 3-year-old frame apartment building in the 5800 block of South Calumet Avenue. The women, ages 51 and 78, and the dog were pulled alive from the rubble, authorities said. No one else was believed to be trapped, but firefighters were continuing their search Sunday night as a precaution, officials said. The women were in hospital in serious condition.