Five armed men raided a small apartment house in the Bronx, tied up the 15 residents, ransacked their homes and fled with their cash and jewelry, police said. The robbers forced their way into the three-story building by claiming to be police on a search for drugs, police said. No one was injured, but $1,600 and personal valuables were taken. Police said the men fired their guns as they fled the neighborhood by car. "People were running around, running into cars--it was like you were watching a cowboy movie," said one longtime resident of the block who was awakened. "The shooting, yelling and screaming . . . we've had a lot of incidents on this block."