At least 32 people, most of them civilians, were killed Monday when suicide attacker struck a military convoy near a busy market in northwest Pakistan, a military official said. The bomber targeted the convoy as it passed through a security checkpost near a crowded bazaar in Alpuri town in Shangla, a district neighbouring Swat valley, a spokesman at the army-run Swat Media Centre said. "Thirty-two people have been killed, 28 of them are civilians and four are security personnel," said Major Mushtaq Khan. "Forty six people are injured, six of them are troops. Five of the troops are in a serious condition. "It was a suicide blast. The attacker was on foot." The troops have cordoned off the area after the attack and launched a search operation after imposition of an unannounced curfew. An exchange of fire continued between the militants and the troops, sources said. President Asif Ali Zardari has condemned the attack. Prime Minister Yousuf Raza Gilani has expressed grief over the losses of life in the attack and ordered probe of the incident.