A man who was killed by two Islamic State gunmen during Sunday service at a church in Istanbul had gone into the building while out for a walk, his cousin said on Monday, while authorities said the attack could have been deadlier if not for a jammed weapon. Authorities said the masked gunmen entered the building and shot dead a 52-year old Turkish citizen, Tuncer Murat Cihan, at the Italian Santa Maria Catholic Church in the Sariyer district. The attackers, one from Tajikistan and another from Russia, have been detained, along with 51 others after the attack.