Several people have been killed and more than 200 have been injured in a huge explosion in the centre of the Afghan capital, Kabul.
Interior ministry spokesman Sediq Sediqqi said a suicide attacker had detonated a vehicle. Gunfire can still be heard.
A Taliban spokesman said the group carried out the attack.
It comes a week after it said it was launching its spring offensive, warning of “large-scale attacks”.
Tuesday’s bombing happened during the morning rush hour in a residential neighbourhood close to the ministry of defence and military compounds.
There are unverified claims that Taliban fighters managed to breach the defences of the National Directorate of Security, the main spy agency which protects high-ranking government officials.
“The blast was carried out by a suicide bomber in a car and possibly one or two bombers are still resisting,” Mr Sediqqi said.
The scene of the attack has been completely cordoned off by Afghan security forces.
The presidential palace, only a few hundred metres from the blast, condemned the attack in the strongest possible terms.
A tweet from President Ghani’s office’s official account suggested the attack “clearly shows the enemy’s defeat in face-to-face battle with ANSDF” – the Afghan National Security and Defense Forces.
The Taliban has over the past years, enjoyed a resurgence, buoyed by the withdrawal of most Nato and US forces at the end of 2014, and a flood of foreign fighters joining their ranks.
It now controls sizeable parts of Afghanistan.