A suicide bomber killed at least three people and wounded 15 others after firing explosives near an outpost in Kabul on Wednesday in the first attack on the Afghan capital in weeks.
Ministry of Interior spokesman Tareq Arian confirmed the number of deaths and described the explosion as "Afghanistan's enemy of civilians in Ramadan month".
The attack appeared to target an Afghan special forces camp on the outskirts of Kabul, a security source told AFP.
No group has taken responsibility for the incident, but Taliban spokesman Zabihullah Mujahid said they were investigating whether their fighters were behind the attack.
The explosion comes as violence increases across Afghanistan. The UN reported earlier this week that attacks in the country had increased after a pioneering US-Taliban agreement was signed in late February that should lay the foundation for a peace process.
The most recent attacks have been limited mainly to rural areas and small towns. Under the US Taliban Agreement, the insurgents have agreed not to attack cities.
The agreement laid a framework to end America's longest war after the invasion of Afghanistan in 2001, which overthrew the Taliban regime just to reappear and spark a deadly uprising.
However, talks between the Kabul government and the Taliban have been derailed in recent weeks.
Dozens of Afghan security forces and Taliban fighters died almost daily, and civilian casualties increased across the country as both sides intensified their operations.
Kabul has been spared most of the violence. However, a series of attacks against minority groups shows that capital remains vulnerable to militants.