A child was killed and 11 others were injured in an explosion at the residence of a Jamaat-e-Islami leader at Shubhaddya North Para in Keraniganj early Thursday.   The identity of the five-year-old could not be known immediately.   Shah Zaman, officer-in-charge of South Keraniganj Police Station, said the explosion took place on the third floor of local Jamaat leader Abul Hossain’s house injuring 12 people.