"We have information that 126 people have been killed in the explosion inside the military training center, eight special commandoes are among the dead," said a senior official in the Defense Ministry in Kabul, speaking on condition of anonymity, Reuters reported.
The official said the assault began on Monday morning when the attackers rammed a car full explosives through a military check point and detonated the vehicle inside the campus of the National Directorate of Security (NDS) forces training center in Maidan Shahr, the capital of Maidan Wardak Province.
Two gunmen entered the campus right after the explosion and shot at many Afghan soldiers before being gunned down during the clashes.
Defense ministry officials said the Taliban had used US-made armored Humvee vehicles captured from Afghan forces as a car bomb in order to breach the military fortifications.
A second source residing in Maidan Wardak Province said more than 100 members of National Directorate of Security (NDS) were killed in the complex attack.
"I have been in touch with the NDS official in the province and they told me that over 100 members of the NDS were killed in the big explosion," the former provincial official said.
Sharif Hotak, a member of the provincial council in Maidan Wardak said he saw bodies of 35 Afghan forces in the hospital.
"Many more were killed. Several bodies were transported to Kabul city and many injured were transferred to hospitals in Kabul," said Hotak, adding that "the government was hiding the accurate casualty figures to prevent a further dip in morale of the Afghan forces."
"The explosion was very powerful. The whole building has collapsed," he said.
Government officials in Maidan Wardak and Kabul declined to comment when asked if they were obscuring the death toll.
Two senior officials in the interior ministry said the exact casualty figures was not being disclosed to prevent unrest within the armed forces.
A senior NDS official in Kabul said at least 50 people were killed or wounded in the complex attack.
President Ashraf Ghani's office in a statement said the "enemies of the country" had carried out an attack against NDS personnel in Maidan Shahr. "They killed and wounded a number of our beloved and honest sons."