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Insurgents attack as investigators travel to Afghan massacre sites

Allauddin Khan / AP

An Afghan villager, right, shows an empty canister allegedly used by US forces during Sunday's killing of civilians at a prayer ceremony for victims in Panjwai, Kandahar province, on March. 13, 2012.

Allauddin Khan / AP

Villagers listen to speeches during a prayer ceremony for victims of Sunday's killing, in Panjwai on March. 13, 2012.

Allauddin Khan / AP

Afghan security forces take up positions in a dried water canal after Taliban militants opened fire on a delegation of senior Afghan officials in Panjwai on March. 13, 2012.

Suspected insurgents opened fire on Tuesday on senior Afghan investigators of the massacre of 16 civilians by a lone U.S. soldier, Afghan officials said, just hours after the Taliban threatened to behead American troops to avenge the killings.

The gunmen shot from long range at two of President Hamid Karzai's brothers, Shah Wali Karzai and Abdul Qayum Karzai, and security officials at the site of the massacre in Kandahar's Panjwai district.

Karzai's brothers were unharmed in the brief battle, which began during meetings with local people at a mosque near Najiban and Alekozai villages, but a soldier was killed and a civilian wounded. 

In Washington, President Obama said he viewed the killing of 16 Afghan civilians as seriously as if those killed had been Americans.

"The U.S. takes this as seriously as if it were our own citizens and our own children who were murdered," Obama said at the White House.

-- Msnbc.com and news services contributed to this post

Jangir / AFP - Getty Images

More than ten years after the beginning of the war, Afghanistan faces external pressure to reform as well as ongoing internal conflicts.