Suicide blasts hit U.S.-Afghan base; 12 killed

Kabul, Afghanistan (CNN) -- Two suicide bombers struck a joint U.S.-Afghan military base in central Afghanistan early Saturday morning, killing 12 people, authorities said.

The attack also wounded 57 others, said Shahidullah Shahid, a spokesman for the provincial governor.

A majority of the casualties included civilians, but four Afghan police officers were among those killed, he said.

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One bomber attacked the base on foot, then another one detonated a truck, the spokesman said.

No international coalition service members died in the attack in Sayedabad district, according to Maj. Adam Wojack, a spokesman for the International Security Assistance Force.

The Taliban claimed responsibility for the attack.

A United Nations report this month stated that violence against civilians fell in the first half of the year.

But even with attacks down compared with the first six months of 2011, violence is taking a "devastating toll on civilians," the United Nations said.

There were 1,145 people killed and 1,954 injured in the first six months of this year, the report found. That's down from 1,510 killed and 2,144 injured in the same period a year earlier.

The drop marked the first time in five years there has been a fall in violence against civilians, the report said.

About 80% of the attacks against civilians are by anti-government forces such as the Taliban, the U.N. said.