Hamas gunmen in the Gaza Strip have arrested members of two radical Islamic groups who were behind a series of attacks on Internet cafes, hair salons, restaurants and hotels over the past year, sources close to Hamas revealed over the weekend. The sources said members of Hamas's paramilitary Executive Force raided the homes of 12 men belonging to the Army of Islam and the Righteous Swords of Islam. During the raids, some of the suspects opened fire at the Hamas militiamen, but no one was hurt, the sources said. The two groups are believed to be affiliated with Al-Qaida. The Army of Islam is headed by gang leader Mumtaz Dughmush, who was behind the kidnapping of BBC correspondent Alan Johnston. "Most of the men who were arrested are university students and teenagers," said one source. "We seized many weapons and explosives in their possession." At least 50 Internet cafes have been bombed over the past 18 months in the Gaza Strip. In addition, many hair salons and restaurants were set on fire or bombed by members of the two groups.