(CNN) -- Six U.S. troops were killed by an improvised explosive device Sunday in eastern Afghanistan, a U.S. official said.
The official asked to remain nameless because he was not authorized to speak about the incident publicly. Earlier in the day, the International Security Assistance Force issued a press release announcing the deaths without offering more details, including the nationalities of the slain troops.
A total of eight international troops were killed over the weekend, according to ISAF, which was first established by the U.N. Security Council in 2001 to secure Kabul and taken over by NATO two years later.
In separate news releases about incidents in southern Afghanistan, the coalition reported one of its servicemembers died Saturday after "an improvised explosive attack" and another was killed Sunday in "an insurgent attack."
The latest attacks came the same day diplomats from around the world convened in Tokyo to discuss Afghanistan's future, including what kind of international assistance the war-torn nation will receive going forward.
U.S. Secretary of State Hillary Clinton said donors at the conference pledged about $16 billion for Afghanistan over four years, a figure that doesn't include money from the United States since any foreign aid must be approved by Congress.
Elsewhere in Afghanistan on Sunday, officials reported at least 26 people killed around the country in roadside bombings.
At least 14 people -- including women and children -- died when bombs detonated around the tractor and truck that they were riding on in southern Afghanistan's Kandahar province, Kandahar Police Chief Gen. Abdul Raziq said. Three others were wounded in that blast.
"This is the act of the enemy of our people who are restlessly trying to kill our innocent people," Raziq said.
Women and children were among 12 people killed in a separate incident near the border crossing with Pakistan used by NATO supply convoys, said Bashir Bangulzai, deputy commissioner of Pakistan's Killa Abdullah district.
And seven people were injured when a bus hit a landmine near Chaman, also in Afghanistan near the Pakistani border, said Bangulzai.
Those eastern Afghanistan explosions, as well as bombing that killed the six NATO troops, follow a deadly week in the region.
Prior to the latest attack, the International Security Assistance Force reported six "innocent civilians" were killed and 28 injured in eastern Afghanistan at the hands of insurgents between June 30 and July 7.
"Despite the efforts of the enemies of government of (the) Islamic Republic of Afghanistan, ISAF forces in eastern Afghanistan remain committed to partnering with their Afghan National Security Forces counterparts to secure a stable and prosperous future for the Afghan people," ISAF said Sunday in a press release detailing the casualties.
CNN's Barbara Starr and journalists Ruhullah Khapalwak and Ayza Omar contributed to this report.