The Ministry of Interior (MOI) said the blast happened close to the Sayeed-ul-Shuhada School in the Dasht-e-Barchi area on Saturday afternoon.
MOI spokesperson Tariq Arian said the number of casualties could increase.
Officials have not revealed the cause of the explosion, or if there was a target. There has been no claim of responsibility yet.
Taliban spokesman Zabiullah Mojahid denied involvement in the explosion in a message to the media.
According to Afghanistan’s Tolo News, the incident happened when students were leaving the school. “A car bomb blast happened first, and then two more explosions occurred near the girls school in Kabul,” said Ibrahim, a schoolteacher, according to Tolo. He added that the majority of victims are girls, Tolo reports.
Violence in the country, at war for two decades, remains unacceptably high, foreign governments and institutions say, calling for an immediate ceasefire between the Afghan government and Taliban.