KARACHI (AFP/Reuters) Heavily armed gunmen in Shikarpur set ablaze more than two dozen trucks and tankers carrying fuel and supplies for NATO forces in Afghanistan, one day after Pakistan closed the border to the convoys. Employing rocket launchers and assault rifles, it was the biggest such attack in Sindh. Ambushes of NATO convoys are not uncommon but are normally concentrated in strongholds of militants in the northwest. Towering walls of flame engulfed the vehicles, which were parked behind a petrol station on the highway leading north from Karachi, the port where NATO supplies are offloaded for the long road trip through Pakistan. Around 20 attackers armed with rocket launchers and assault rifles attacked these trucks. They set ablaze 27 trucks parked there, Shikarpur district police chief Abdul Hameed Khoso told AFP of the pre-dawn attack. Some of the tankers have been completely destroyed and others partially. But there is no loss of human life, Khoso said. Police said they had picked up around 10 suspects including five netted from a raid on a Madrassa. They were scouring the area for leads after the attack, which has shocked the south. This is the first major attack on NATO trucks in Sindh, Sindh provincial government spokesman Jamil Soomro confirmed to AFP. The police chief, Khoso, said: We suspect that some elements belonging to extremist organisations are behind the attack, who want to disrupt peace.