KABUL, Dec. 11 (Xinhua) -- Several militants and one Afghan civilian were feared killed and over 50 civilians wounded after assailants launched bomb attacks outside a main U.S. and NATO military base in Bagram district of eastern province of Parwan on Wednesday morning, a local official said.

Two massive explosions occurred roughly at 05:50 a.m. local time when the first group of attackers exploded two car bombs outside the south wall of the base, where scores of houses, shops and a mosque were damaged, local Tolo News TV reported.

"The second group of militants seized an abandoned health facility. They tried to target foreign forces and attack with heavy weapons the military base," the report said

"The initial information found that more than 50 villagers were wounded in the incident that occurred in Janqadam, a locality in adjacent of Bagram airbase. The wall of the base has absorbed force of explosions but the blasts caused massive destruction," district chief Abdul Shakor Qudosi told the TV.

He said most of the wounded were affected by flying glasses, debris and shrapnel.

"The injured were shifted to hospitals in Bagram district, provincial capital Charikar city and national capital Kabul," the official noted.

Afghan troops and U.S. forces sealed off the area following the attack.

Located in the Bagram district of eastern Parwan province, the Bagram military base, some 50 km north of Afghan capital of Kabul, has been serving as a main U.S. and NATO military base in Afghanistan over the past 18 years.

The blasts caused a plume of gray smoke to rise above the scene and the sound of the blasts was heard in Kabul.

Casualties of the security forces remained unknown.

No group has claimed responsibility for the attack yet.