Four children were killed and five other people injured when a shell hit a house in north Sinai, Aswat Masriya website reported.
The shell was reportedly fired by militants targeting the Egyptian military, according to a security source.
Militants have been escalating attacks against security forces, especially in north Sinai, since the ouster of Islamist president Mohamed Morsi last year.
More than 500 members of the security forces have been killed in attacks over the last year.