Tel Aviv  - A Palestinian armed with a knife infiltrated a Jewish settlement on the central West Bank Monday morning and stabbed three Israelis before being shot by an armed settler, a military spokeswoman in Tel Aviv said.

She said one of the three Jewish settlers stabbed was in serious condition, while the other two were moderately and lightly wounded.

The spokeswoman said the attacker was apparently killed after being shot.

The incident occurred in the settlement Qiryat Sefer, near the West Bank city of Ramallah.

It came after thousands of Arab Israelis within Israel proper, too, on Sunday protested a massive Israeli air offensive in the Gaza Strip, which since it started late Saturday morning killed more than 300 Palestinians.

Some 20,000 protested in the Arab town of of Umm el-Fahm alone, northern Israel, while clashes also raged between Israeli police and stone-throwing Palestinians in East Jerusalem.

Police said that at least 50 Arab Israelis and Palestinian residents of East Jerusalem were detained after throwing stones and bottles.

Protesters also threw a Molotov cocktail near the Arab Israeli town of Baka al-Garbiyeh, located near the green line separating central Israel and the West Bank.

Police Spokesman Micky Rosenfeld said police remained on high alert, particularly in Jerusalem and northern Israel, where many Arab villages are concentrated, to prevent more "riots or attacks as a result of this campaign" in Gaza.

Police were also holding dialogues with village leaders to calm tempers, he said, and would allow non-violent protests coordinated with them in advance. (dpa)