By Donita NaylorWOONSOCKET, R.I. -- An 18-month-old boy died Monday afternoon as a result of a wooden bookshelf tipping over onto his chest, police officials said in a news release. Police and rescue personnel were called to 113 Parker St. for a medical emergency, and the boy was taken to Landmark Medical Center, where he was later pronounced dead. The investigation is continuing, the news release said.