A suicide bomber has blown himself up inside the Afghan defence ministry in Kabul, killing a bodyguard for the deputy minister and injuring at least three others, according to local television reports.
Monday's attack was the third major attack inside an Afghan security force compound in four days.
The Taliban claimed responsibility for the attack.
The attacker got into the building wearing an army uniform and with a defence ministry pass, Tolo television said.
The defence ministry's spokesman could not be reached for comment.
Hashmat Stanekzai, a spokesman for the Kabul police chief, confirmed there had been an "incident" in the ministry, but declined to comment further.
The injured included an assistant to the defence minister and secretary of the army chief of staff, the report said, quoting unidentified defence ministry sources.
Al Jazeera's correspondent Hashem Ahelbarra, reporting from Kabul, said: "There were three suicide bombers, dressed in military uniforms, and they managed to get through three to four security checkpoints into the ministry of defence.
"The ministry of defence is adjacent to the presidential palace and it is one of the most heavily fortified places.
"One of them got to the third floor, blew himself, killing the bodyguard of the deputy minister and injuring three others.
"The second suicide bomber was shot dead and search is underway for the third suicide bomber. Taliban has claimed responsibility for this attack."
It was not immediately clear if the assailant was an enlisted soldier or a fighter who had managed to get past ministry security, disguised in the military uniform.
Taliban fighters have said that Gerard Longuet, the French defence minister who is visiting Afghanistan, was the target of the attack, according to reports.
The attack comes months before the start of transfer of security responsibilities from foreign to Afghan forces, and after NATO-led troops claimed solid progress in efforts to bolster the numbers and quality of the Afghan police and army.
On Saturday, a suicide bomber in an Afghan army uniform penetrated a desert base in the east of the country and killed five foreign and four Afghan soldiers, the highest toll of NATO-led troops in a single attack for several months.
And on Friday, a suicide bomber in police uniform evaded tight security at the police headquarters in Kandahar city and killed Khan Mohammad Mujahid, Kandahar province's police chief.