GAZA CITY, Gaza Strip — Turmoil from the battle between Israel and Hamas spilled over into the West Bank on Friday, sparking the most widespread Palestinian protests in years as hundreds of young demonstrators in multiple towns clashed with Israeli troops, who shot and killed at least 11 people.

Israel intensified bombardment of the Gaza Strip with a furious overnight barrage of tank fire and airstrikes that wreaked destruction in some towns, killed a family of six and sent thousands fleeing.