Armed militants in Afghanistan stormed a key government security agency in the capital Tuesday morning as part of a coordinated assault, killing at least 28 people and wounding more than 320.

The Taliban claimed responsibility for the attack, which included a suicide car bombing. It appeared to have targeted an agency similar to the U.S. Secret Service, providing personal protection for high-ranking government officials.

Sediq Sediqqi, spokesman for the Interior Ministry, said during a press conference that two militants were involved in the attack. One drove the small truck rigged with hundreds of pounds of explosives. The second entered the compound in the aftermath of the explosion and opened fire before he was eventually killed.

Sediqqi said the car bomb caused massive damage to buildings and vehicles in the area and added that the death toll could rise.

Data curated by FindTheData

"With no doubt there was a security vacuum and that needs to investigated, it is too early to comment on that right now," he said.

The U.S. Embassy denounced the attack, calling it a senseless act of violence. It added that it supports the Afghan government's peace process to end such violence.

"Today's attack shows the insurgents are unable to meet Afghan forces on the battlefield and must resort to these terrorist attacks," added Gen. John W. Nicholson, commander of international forces in Afghanistan. "We strongly condemn the actions of Afghanistan's enemies and remain firmly committed to supporting our Afghan partners and the National Unity Government."

Ismail Kawasi, spokesman for the Public Health Ministry, said so far 327 are wounded, including women and children, have been brought to area hospitals. An Interior Ministry statement said that dozens of civilians were killed and wounded in the attack. The casualty figures are expected to rise.

"This was one of the most powerful explosions I have ever heard in my life," said Obaidullah Tarakhail, a police commander who was present when the attack began. Tarakhail said he couldn't see or hear anything for 20 minutes after the initial explosion. "All around was dark and covered with thick smoke and dust," he said.

Dozens of civilian apartment buildings, houses, shops and several government buildings were damaged by the car bomb blast.

Taliban spokesman Zabihullah Mujahid claimed responsibility for the attack. Taliban insurgents have stepped up their attacks recently since announcing the start of their spring offensive last week.

Data curated by FindTheData

President Ashraf Ghani issued a statement condemning the attack and saying it, "clearly shows the enemy's defeat in face-to-face battle with Afghan security forces."

In separate statement the UN Assistance Mission in Afghanistan (UNAMA) condemned the attack in Kabul.

"This attack shows the devastation caused by the use of explosive devices in urban areas and once more demonstrates complete disregard for the lives of Afghan civilians," said Tadamichi Yamamoto, the Secretary-General's Deputy Special Representative for Afghanistan. "The use of high explosives in civilian populated areas, in circumstances almost certain to cause immense suffering to civilians, may amount to war crimes."

The attack comes four days after another attack by Taliban insurgents in northern Kunduz province which was repelled by the Afghan security forces.

Officials in Kunduz said that security has improved in the city and that the Taliban were defeated in other parts of the province, but operations were still underway to clear militant fighters from the rest of the province.

The Taliban held Kunduz for three days last year before being driven out by a two-week counteroffensive aided by U.S.-airstrikes. It was their biggest foray into an urban area since 2001.

The Associated Press contributed to this report.