A blast has rocked a shrine packed with pilgrims in the Afghan capital, Kabul, causing many casualties, reports say.
At least 20 people were killed, reports say, with many other injured. Officials say the blast was caused by a suspected suicide bomber.
Another blast hit a mosque in the northern city of Mazar-i-Sharif at about the same time, with reports of four dead.
Shia Muslims are commemorating Ashura, a national holiday in Afghanistan.
It is the climax of Muharram - the month of mourning for the martyrdom of the Prophet Muhammad's grandson.
The blasts happened at about 1130 (0730 GMT).
The BBC's Quentin Sommerville in Kabul says it seems to be a co-ordinated attack with a sectarian element, with the Shia community the target.