Militants detonated a car bomb before storming a Kabul government compound in an ongoing attack on Monday, officials and witnesses said, in the latest violence to rock the Afghan capital.

A number of gunmen raided the compound where the Ministry of Public Works and other offices are located, interior ministry deputy spokesman Nasrat Rahimi said.

Afghan security forces have killed two of the attackers and freed 200 employees trapped inside one of the buildings occupied by the militants, Rahimi said.

“There are still some hostages with the enemy and a clearance operation is ongoing,” he said. At least four people have been wounded, said health ministry spokesman Wahid Majroh.

One had broken several bones after jumping from the third floor of a building to escape the attackers, an AFP correspondent at a hospital said.

Another two were wounded by broken glass.

There was no immediate claim of responsibility for the raid that began with a bomb-laden vehicle exploding at the entrance. That was followed by a second blast, interior ministry spokesman Najib Danish said, though he did not specify the nature of it.

Plumes of black smoke could be seen rising from the compound, with at least two military helicopters circling above.

Journalists near the scene reported hearing numerous explosions in the hours after the attack began. Ashraf, a witness who works at the Ministry of Public Works and who goes by one name, said militants inside the compound were exchanging gunfire with security forces.

“They are also firing at the NDS facility nearby,” he told AFP after escaping the compound, referring to the Afghan spy agency, the National Directorate of Security.

Public works ministry spokesman Mehdi Rohani told AFP he and his colleagues were fleeing to a safe room. “A car bomb detonated at the entrance of the ministry's parking lot,” he told AFP by mobile phone as he ran from the scene.

“I can hear some gunfire outside the building. We are fine.”

Soft targets

The attack caps a tumultuous few days for Afghanistan after an American official told AFP late last week that President Donald Trump had decided to pull out “roughly half” of the 14,000 US forces in the country.

The unexpected move stunned and dismayed foreign diplomats and Afghan officials in Kabul who are intensifying a push to end the 17-year conflict with the Taliban.

The assault also comes a day after President Ashraf Ghani appointed Amrullah Saleh and Assadullah Khaled, both former spymasters known for their anti-Taliban and Pakistan stance, to head the interior and defence ministries, respectively.

Militants have previously attacked government ministries and departments because they are often poorly defended and seen as soft targets.

Monday's attack was the biggest in Kabul since November 28 when the Taliban detonated a vehicle bomb outside the compound of British security firm G4S, killing at least 10 people and leaving a massive crater in the road.

While there has been no official announcement of a US drawdown, the mere suggestion of the United States reducing its military presence has rattled the Afghan capital and potentially undermined peace efforts. General Scott Miller, the top US and NATO commander in Afghanistan, said Sunday he had not received orders to pull forces out of the country. Trump's decision apparently came Tuesday as US peace envoy Zalmay Khalilzad met with the Taliban in Abu Dhabi, part of efforts to bring the militants to the negotiating table with Kabul. Many Afghans are worried that President Ashraf Ghani's fragile unity government would collapse if US troops pulled out, enabling the Taliban to return to power and potentially sparking another bloody civil war.