A suicide car bomber detonated his vehicle in central Kabul as armed militants attacked a government security agency in the city. The massive blast took place near the defence ministry in the Afghan capital on 19 April, sending a stream of thick black smoke into the sky.

At least 28 people were killed and more than 300 wounded, officials said. The explosion was followed by bursts of gunfire as a number of gunmen launched an assault in the area that has been sealed off by authorities.

"Security forces are in a fight with an unknown number of armed insurgents right now," Mohammad Afzel, a police officer at the site, told AP. The attack, which was claimed by the Taliban, is believed to have targeted a security agency tasked with protecting high-ranking government officials.

Interior ministry spokesman Sediq Sediqqi told AFP: "The first blast was carried out by a suicide bomber in a car and possibly one or two bombers are still resisting. The scene of the attack has been completely cordoned off by Afghan security forces."

President Ashraf Ghani condemned the attack in the "strongest possible terms", in a statement that deplored the loss of lives of innocent civilians. He said "many" people had been killed and injured in the attack, but did not specify a number.

"Today's terrorist attack near Pul-e-Mahmud Khan, Kabul clearly shows the enemy's defeat in face-to-face battle with ANSDF (Afghan National Defence and Security Forces)," Ghani added on Twitter.

The Public Health Ministry later confirmed 327 injured people, including women and children, were so far taken to local hospitals. Police put the number of fatalities to 28. Reuters reported that sirens were heard from the US embassy compound, but the embassy said that it was unaffected by the explosion.

The incident came just a week after the Taliban announced its annual spring offensive, vowing "large-scale attacks" against government strongholds in a bid to oust the Western-backed leadership from power.