An injured boy is taken the medical treatment in the al-Shifa hospital in Gaza City, following shelling by Israeli forces in the Beit Lahiya area, to the north of Gaza City. (Reuters)

Al Qassam Brigades, armed wing of the Islamic Resistance Movement (Hamas), vowed on Tuesday to avenge an Israeli killing of eight Palestinians in a tank shell attack in thenorthern Gaza Strip town of Beit Lahya.

"Our response to this criminal massacre will be continuous rocket and mortar attacks on Jewish settlements until the Zionists leave our territories," the group said in a leaflet.

The group also criticized Palestine Liberation Organization chief Mahmoud Abbas for his recent remark that rocket attacks on Israeli targets are not useful, slamming it as "very dangerous withnegative impact on our legal resistance."

Palestinian medics and witnesses said eight Palestinians were killed on Tuesday morning and seven others injured after Israeli tanks fired shells at the town of Beit Lahya in northern Gaza Strip.

Witnesses said when pupils were on their way to school and farmers were on their way to the field to harvest strawberries at around 7 am (0500 GMT), Israeli tanks fired shells at the main street of the small town.

Palestinian medics at Kamal Odwan Hospital in northern Gaza saidthe hospital received eight bodies, four of the killed under 17, and seven people were also wounded, four of them in critical conditions.

Abbas condemned the killing, terming it as "a serious Israeli escalation against our people."

He said such an escalation could obstruct the Palestinian presidential election due on Jan. 9.

Hamas retaliates with rocket attacks on Israel

Hamas militants mounted rocket attacks on Israeli targets Tuesday shortly after Israeli army tank shells killed eight Palestinians in northern Gaza Strip.

Ezel Dein al Qassam brigades, the armed wing of Islamic Resistance Movement (Hamas), claimed responsibility for firing Qassam rocket at the Jewish settlement of Nisaneet in northern GazaStrip.

The brigades said its militants managed to launch another Qassamrocket on the Israeli town of Sderot.

Meanwhile, Israeli army radio reported Palestinian militants fired two Qassam rockets on Sderot but no causalities were reported.

The attack came in response to the Israeli crime against the Palestinian people in Beit Lahiya, said the brigades, adding the Palestinian people would continue resistance till forcing the enemy out of the Palestinian lands.