GARDEZ, Afghanistan – A suicide bomber apparently targeting a U.S. convoy killed 14 people and wounded 31 in a crowded eastern Afghan market Sunday, witnesses and officials said said.

The powerful explosion in the city of Gardez damaged around 30 shops, shattering windows and destroying the closest stores.

Witnesses said a U.S. convoy appeared to be the target. 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.

Nasar Ahmad, a 30-year-old shopkeeper whose three cousins were seriously wounded in the blast, said he saw a U.S. convoy driving through the city just before the explosion.

“I heard a strong blast and then saw a fireball go up,” Ahmad said from his hospital bed. “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 were Afghan civilians.

“The convoy had already passed when the attack happened,” he said.

The blast came a day after a suicide bomber in northern Afghanistan killed three German soldiers and seven civilians.

Ghulam Hazrat Majedi, the doctor in charge of the Gardez hospital, said two of the 31 wounded were in critical condition.

In the eastern province of Ghazni, 30 Taliban fighters were killed during a battle with ISAF and Afghan forces on Saturday, said Mohammad Qazam Allayar, the deputy provincial governor. He said 18 Taliban were injured and 11 arrested.

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 U.S., NATO and Afghan officials. The dead have mostly been militants, but about 300 civilians have also been killed.

An ISAF statement 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.