More than 150 people were wounded in the attack, the biggest in recent weeks, as Afghanistan's leadership grapples with a political crisis and a security vacuum as most foreign troops pre-pare to leave the country.
Ghazni provincial governor Musa Khan Akbarzada said that a group of 19 insurgents was involved in the simultaneous attacks on the local office of the National Directorate of Security (NDS) and a quick reaction team housed in the police building.
The men armed with light machine guns drew up in trucks at a back gate of the NDS, the crack US-trained agency leading the fight against the insurgency, and the police building and exploded their bombs.
Mr Akbarzada said: "The bombs were so powerful that many civilians were woun-ded because of falling roofs and shattering of windows in their homes."
Soon after, several of the attackers entered the NDS compound and fought a gunbattle with Afghan forces.
Dozens of the wounded were taken to a lone hospital in Ghazni where doctors were forced to treat many of them outside.
The attack in Ghazni, one of the provinces that sur-round the capital city of Kabul, is the latest in a series of offensives launched by the Taliban in the summer fighting season.
Insurgents have carried out complex attacks on government installations, including in Logar and Wardak provinces.