A suicide bomber walked into a crowded market in eastern Afghanistan and blew himself up on Sunday, killing 14 people and wounding 31, just after a US convoy drove by, officials and witnesses said. The attack in the city of Gardez damaged some 30 shops, shattering wiGARDEZ, Afghanistanndows and destroying the stores closest to the explosion. Three vehicles were damaged, including a taxi blasted by dozens of pieces of shrapnel. Witnesses said a US convoy appeared to be the target, and Maj. William Mitchell, a spokesman for NATO's International Security Assistance Force, said there were initial reports of injuries to ISAF soldiers, though he didn't have further details. Six people died at the scene of the blast, police said. Another eight later died at the hospital, according to Ghulam Hazrat Majedi, the doctor in charge of the Gardez hospital. He said two of the 31 people wounded were in critical condition. Afghan soldiers donated blood for the wounded. Nasar Ahmad, a 30-year-old shopkeeper whose three cousins were seriously hurt in the blast, said he had seen a US convoy driving through the city just before the explosion. "I heard a strong blast and then saw a fireball go up," Ahmad said from the Gardez hospital. "For 10 minutes, I couldn't hear, and I didn't know where I was. I saw a lot of people injured, lying in the street." Shah Mohammad, 19, said all those killed or wounded by the blast had been Afghan civilians. "The convoy had already passed when the attack happened," he said. The blast in Gardez came one day after a suicide bomber in northern Afghanistan killed three German soldiers and seven civilians. Violence in Afghanistan has increased sharply in the last several weeks. More than 1,600 people have been killed in insurgency-related violence this year, according to an AP count based on US, NATO and Afghan officials. The dead have mostly been armed insurgents, but about 300 civilians have also died in the violence. On Saturday, 30 Taliban fighters were killed during a battle with ISAF and Afghan forces in the Ghazni province, said Mohammad Qazam Allayar, the deputy provincial governor. He said 18 Taliban were wounded and 11 arrested. A statement from NATO's ISAF said that during the last several days, Afghan and ISAF operations "have resulted in the removal of over 100 enemy fighters." The ISAF press office said it wasn't immediately clear what the word "removal" meant. The statement said local Afghans are increasingly cooperating with military and government units. "The people have said, 'Enough to the bloodshed and intimidation,' and are reporting criminals and insurgents. They are also closing off their lands and villages to them," said Maj. Donald Korpi, a spokesman with the unit involved in the Ghazni battles.