Four people were killed and 17 wounded by a suicide bomber who blew himself up near a group of Shia pilgrims in a town north-east of Iraq's capital on Monday. The bomber detonated his explosive vest after a policeman stopped him from approaching the pilgrims in the town of Balad Ruz, 90 km (55 miles) north-east of Baghdad, the Diyala province security operations centre and a police source said.