The US deaths came a day after six coalition troops were killed and many more were injured in simultaneous attacks in the holy city of Karbala. At least seven locals were also killed and some 80 more injured. Among the coalition dead were four Bulgarian troops and two from Thailand. 'It was a co-ordinated, massive attack planned for a big scale and intended to do much harm,' said the head of the Polish-led peacekeeping force in the region, Andrzej Tyszkiewicz. 'Four car bombs were used, as well as grenade launchers and guns.' The deaths occurred when militants struck at coalition posts at the Ahil al-Biet University and the governor's offices in the city.