Myanmar police fired on protesters around the country on Sunday in the bloodiest day of protests since demonstrations against a military coup started. At least 18 people were killed, the U.N. human rights office said. Police were out in force early and opened fire in different parts of the biggest city of Yangon after stun grenades, tear gas and shots in the air failed to break up crowds. Several wounded people were hauled away by fellow protesters, leaving bloody smears on pavements, media images showed. The protesters who are demanding the release of elected government leader Aung San Suu Kyi detained during the Feb 1 coup.