The driver of a bomb-laden car and six gunmen attacked the parliament building in Kabul the capital.
Exact casualty numbers are still being confirmed, but the attack left at least 19 people injured and sent a plume of black smoke across Kabul.
The explosion was broadcast live on Afghan television. Dramatic scenes show parliamentary business interrupted by a loud bang and the room filling with smoke. Surreal video shows the speaker remaining still and calm as the room becomes engulfed in dust and smoke.
The attack began when a Taliban fighter driving a car loaded with explosives blew himself up outside parliament gates, said Ebadullah Karimi, spokesman for Kabul police.
Six gunmen took up positions in a building near parliament, he said. Security forces killed the six after a gun battle lasting nearly two hours.
This morning’s attack, the most brazen in years, raises questions about the Nato-trained Afghan security forces’ ability to cope and how far the militants can advance.
The explosive-laden car was able to bypass several security checkpoints to reach the parliament gates. Elsewhere in the country a second district in two days fell to the Islamist group.
Taliban spokesman Zabihullah Mujahid claimed responsibility saying: “We have launched an attack on parliament as there was an important gathering to introduce the country’s defence minister.”
Mohammed Masoom Stanekzai, who was due to be sworn in as defence minister, has been a top official in the government body overseeing the country’s peace process.
Violence has spiralled in Afghanistan since the departure of most foreign forces at the end of last year. The insurgents are pushing to take territory more than 13 years after the US-led military intervention that toppled the Taliban from power.