Attackers gunned down a police officer Saturday in Kirkuk, then bombed a funeral procession carrying his corpse, killing three other policemen and wounding two, officials said, as protesters in Europe marked the second anniversary of the U.S.-led invasion of Iraq. The attackers sprayed automatic-weapons fire from a vehicle, killing the policeman as he made his way to the station house early Saturday, police Capt. Ahmed Shinrani said. Hours later, a roadside bomb hit mourners and security forces transporting the corpse for burial. "This is a criminal act. The mourners were doing a religious duty. I don't understand how someone could blast a funeral," wailed Allaa Talaban, sister of one of the officers killed in the blast in Kirkuk, an oil-rich city 180 miles north of Baghdad.