An 18-year-old student was killed and seven others aged between 13 and 26 were wounded when an explosive device went off in Arish, North Sinai, late on Sunday, according to security sources.
The bomb was planted in a street, apparently aimed at security forces, but it exploded as the civilians were passing by, sources said.
Five of the casualties are in a serious condition and receiving medical care, they added.
Islamic State affiliates in the restive Sinai Peninsula have claimed responsibility for most of the bloody attacks that have killed hundreds of policemen and soldiers since the overthrow of the Muslim Brotherhood government in 2013.
Most of North Sinai is under a partial curfew in force since October 2014.
Edited translation from Al-Masry Al-Youm