CAIRO, July 22 (Aswat Masriya) Unknown gunmen killed on Tuesday a security guard who was on his way home in North Sinai's Arish, security sources said.

The assailants mistook the guard of an engineering institute for a policeman, the sources added.

Since former President Mohamed Mursi's ouster last July, militants in Sinai escalated their attacks on army and police forces and installations.

Islamist militants in Sinai have claimed responsibility for several attacks and bombings in Cairo as well as other cities.