A suicide bomber rammed his car packed with explosives into a bus carrying government employees in the Afghan capital early on Monday, killing 24 people and wounding 42 others, Kabul's police chief spokesman said. The Taliban claimed responsibility for the assault.
The bombing continued the unrelenting violence that has killed more than 1,700 civilians in Afghanistan so far this year.
The Taliban, which is battling the Western-backed government and a NATO-led coalition for control of Afghanistan, has launched a wave of attacks around the country in recent days, sparking fighting in more than half a dozen provinces.
"I was in my shop when suddenly I heard a terrible sound and as a result all of my shop windows shattered," said Ali Ahmed, a resident in the area of Monday's blast.
Government security forces said a small bus owned by the Ministry of Mines had been destroyed in the blast but the National Directorate for Security, the main intelligence agency, said none of its personnel had been hit.
Three civilian vehicles and 15 shops were destroyed or damaged in the blast, the Interior Ministry said in a statement.
At least 1,662 civilians had already been killed in Afghanistan in the first half of the year.
Kabul has accounted for at least 20 percent of all civilian casualties this year, including at least 150 people killed in a massive truck bomb attack at the end of May, according to United Nations figures.
The resurgence of violence also coincides with the U.S. administration weighing up its strategic options for Afghanistan, including the possibility of sending more troops to bolster the NATO-led training and advisory mission already helping Afghan forces.