KABUL, Afghanistan - The boy, dressed in white and thought to be no older than 13, appeared amid the din of a wedding party in a small southern Afghanistan village and walked up to within 15 feet of a cluster of tables where everyone was eating. As he prepared to detonate his suicide bomb vest, the gathering flew into a panic.

"Everyone immediately tried to escape," said Abdullah Jan, a guest at the wedding. But there was no time.

The boy's suicide vest detonated, killing more than 40 people and wounding at least 80 others, said Zemarai Khan, a local police chief who was at the wedding.

Carried out late Wednesday in a small village in Kandahar province, the attack underscored the vulnerability of Afghan society even as President Hamid Karzai pursues negotiations with Taliban insurgents who have waged war with his government and Western forces for nearly nine years.

The Taliban has scoffed at Karzai's peace offer and has carried out a wave of deadly attacks since the Afghan leader convened a national peace conference in Kabul last week.

The bombing of the wedding in the village of Nagahan in the Arghandab district was the deadliest of those attacks. The bomber, who witnesses said was either 12 or 13, targeted a housing compound where men and young boys were celebrating the wedding, authorities said. Female guests were situated in a different area. The groom was injured in the blast but survived, Jan said. His brother was killed.

Though authorities have not determined why the wedding was targeted, witnesses said the groom and several members of his family were Afghan police officers. Nagahan is also a village where locals have formed a tribal militia to help keep Taliban militants from infiltrating their area.

The Wednesday blast happened during a spike in bloodshed, the Associated Press reported. At least 20 U.S. service members have been killed in Afghanistan this month - including an American who died yesterday from a roadside bombing. The victim's name was not released.