A suicide car bomb explosion happened close to National Directorate of Security (NDS) forces training center in Maidan Shahr, capital of Wardak province, on Monday morning, local officials confirmed.
The incident happened at about 7am local time after a car bomb exploded close to a base where Afghan NDS forces are stationed, a spokesman for provincial governor Rahman Mangal said.
Provincial public health officials confirmed that the militants' attack left 24 killed or wounded, but a provincial council member said the number of casualties killed and wounded is more than 50.
Officials have not commented yet about the precise number of causalities.
Eyewitnesses said that at first a suicide attacker detonated a Humvee full of explosives close to the center and then four other attackers clashed with the forces.
According to eyewitnesses all the attackers were dressed in NDS uniforms.
Eyewitnesses said that the area was under siege, yet ambulances were transferring the wounded.
Although the attackers were gunned down by the forces after five hours of clashes, dozens of forces were piled up under the ruins of a collapsed building.
Taliban claimed responsibility for the blast and said a group of attackers had stormed the base.
President Ashraf Ghani in a statement condemned the Wardak attack and called it a terrorist act and he also expressed his condolences, ordering relevant officials to investigate the attack and provide assistance to the victims and their families.