A squad of Israeli troops trapped in Bethlehem by hundreds of Arab college students during an anti-Israel protest opened fire, wounding three people, one of them seriously, military sources said in Jerusalem. One of the victims, a 22-year-old student at Freres University, was in "very grave" condition with a gunshot wound in the head, a hospital spokesman said. The other two victims suffered minor wounds. Witnesses said more than 400 students were protesting the occupation of the West Bank. The level of unrest has escalated in the wake of recent slayings of seven suspected Arab guerrillas by Israeli troops in Gaza.