Fighting between Israel soldiers and those of the occupied territories have spread across much of the occupied West Bank after days of hostility in Gaza, The Associated Press reported Saturday.

The spillover of clashes triggered the most widespread protests in the occupied territories in years as hundreds of young demonstrators in several towns clashed with Israeli forces, who shot and killed at least 11 people.

Israeli stepped up air attacks in Gaza and Hamas militants responded by firing missiles into Israel as the conflict entered its fifth day. 

The Israeli military said the airstrikes involved 160 jets dropping some 80 metric tons of bombs within an hour - destroying a network of tunnels built by Hamas, The Associated Press said.

Palestinian health officials said at least 12 people were killed in the air assault in Gaza. Medical professionals said a woman and her three children were among those killed after a hit on a refugee camp.

At least 132 people have been killed in Gaza since Monday, including 32 children and 21 women, with 950 others injured, Palestinian authorities said.

The number of deaths and injuries from the airstrike is seen to increase. Residents of Gaza said they were given no warning before the attack, according to The Associated Press.

Meanwhile, the fighting in the West Bank marks an escalation of some of the worst clashes in the region in years. At least 10 Gaza residents were reported killed in the West Bank violence, while hundreds have been wounded, the BBC reported.