KABUL, Afghanistan — Just like any other day, Zareen Gul, 60, held the hand of her grandson, Ali Seyar Nazari, 10, and left home to attend the early evening prayer in their neighborhood mosque in the west of Kabul.

This time, however, they did not return home. Their family found their remains, barely identifiable from the clothes they wore, at a hospital after an Islamic State suicide bomber targeted the prayer.

Ms. Gul and young Seyar became the latest victims of what has been one of Afghanistan’s deadliest weeks. The death toll from twin attacks on mosques late on Friday, just hours apart, was raised on Saturday to at least 67 people killed and dozens wounded. As many as 88 may have died in the two attacks.

More than 200 people, both civilians and security personnel, have been killed this week in Afghanistan in six attacks. A precise casualty total is hard to get, as varying levels of violence rage in more than half the country’s provinces.