An explosion near a school in the western part of the Afghan capital Kabul on Saturday killed at least 25 people and wounded dozens more.
Interior Ministry spokesman Tariq Arian said at least 52 people, most of them students, were injured in the blast.
He did not specify the cause or the target of the explosion.
Ghulam Dastagir Nazari, spokesman for the health ministry, said 46 people had been taken to hospitals so far.
Kabul is on high alert since Washington announced plans last month to pull out all US troops by September 11 with Afghan officials saying Taliban have stepped up their attacks across the country.
No group has claimed responsibility for Saturday's blast.
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