At least 14 people were killed and 31 wounded when a suicide bomber blew himself up in a crowded Afghanistan market on Sunday, just missing a U.S. convoy.

The bomber, who was on foot, struck in the city of Gardez. The force of the blast damaged about 30 shops, shattered store windows and demolished stores closest to the blast, The Associated Press reports.

Witnesses said the bomber appeared to be targeting the U.S. convoy.

Maj. William Mitchell, a spokesman for NATO's International Security Assistance Force, said there have been reports of injuries to ISAF soldiers, but no further details have been released.

Police report that six people were killed at the scene. Later, eight of the injured died in hospital, according to Ghulam Hazrat Majedi, the doctor in charge of the local hospital.

Another two of the injured were said to be in critical condition.

Witnesses described the chaos that ensued after the bombing.

"I heard a strong blast and then saw a fireball go up," Nasar Ahmad, a shopkeeper whose three cousins were hurt in the blast, said from the hospital where he was being treated along with his relatives.

"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," he told AP.

Another witness said the target appeared to be the U.S. convoy, but it was detonated too late, and all those injured or killed were Afghan civilians.

"The convoy had already passed when the attack happened," said 19-year-old Shah Mohammad.

On Saturday, a suicide bomber killed three German soldiers and seven civilians in northern Afghanistan. And in Ghazni province, 30 Taliban fighters were killed, 18 were injured and 11 were arrested in a gunfight with ISAF and Afghan forces

And on Friday, a suicide car bomber rammed his vehicle into a government convoy Thursday, killing three people on the street and wounding the information minister, according to the governor of Kandahar province.

Kandahar Gov. Asadullah Khalid -- believed to be the intended target of the Friday attack -- said the explosion killed three civilians on the street and slightly wounded Information and Culture Minister Abdul Karim Khurram and his chief deputy.

Both men were riding in an armoured vehicle in the convoy.

Violence has been on the rise in Afghanistan in recent weeks. More than 1,600 people have been killed so far this year in insurgency-related violence, AP reports.

Of those, about 300 were civilians while the rest were believed to be militants.

An ISAF statement said that Afghan and ISAF operations in the last few days "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 from ISAF also said cooperation is increasing between local Afghans and military and government units.

With files from The Associated Press