By Nidal al-Mughrabi
Israel has stepped up military action against Hamas since it claimed responsibility for a Palestinian suicide bombing on Monday, the first such attack by the Islamist faction inside the Jewish state since 2004.
Hamas, the ruling Islamist group, said five of its gunmen were killed fighting the Israeli troops. Another gunman, from Islamic Jihad, also died in the clashes, it said.
Two of the wounded were initially identified as fellow staff members but the Education Ministry later said all three were pupils aged 16.
An Israeli military spokeswoman said troops had fired on a Palestinian rocket crew spotted inside Beit Hanoun.
The military spokeswoman confirmed there had been an incursion in Jabalya and said forces withdrew after a few hours.
In the West Bank city of Ramallah, the executive committee of the Palestine Liberation Organisation called on Israel to stop "operations of killing and destruction ... including aggression against houses and schools".
Israel quit Gaza in 2005 after 38 years of occupation but still controls its coast, key crossings and airspace. Hamas and other factions regularly launch crude rockets across the border.
Seven rockets were launched from Gaza on Thursday, the army said. One hit the border town of Sderot, hurting two Israelis.
(Additional reporting by Joseph Nasr in Jerusalem and Mohammed Assadi in Ramallah, Writing by Dan Williams, Editing by Robert Woodward)
