QUETTA  - A bomb attached to a bicycle killed a boy and injured at least 11 other people at a police checkpoint in Quetta Monday, police said.The bicycle was parked at the checkpoint and its four-kilogram bomb was detonated by remote control, Quetta police chief Mir Zubair Mehmood told AFP.“At least 12 people, including four policemen, were wounded,” Mehmood said.Asif Ghafoor, another senior police officer, said a 12-year-old boy who was among the wounded died later in hospital.Mohammad Babel, a rescue official, also confirmed the boy’s death. Bomb attacks frequently target government security personnel in Quetta.