mother, father and their 4-month-old infant, stabbed to death in their bed. In the next room, medics say they found the body of an 11-year-old sibling.

A grisly trail of toys and blood led paramedics to the first three bodies: a mother, father and their 4-month-old infant, stabbed to death in their bed. In the next room, medics say they found the body of an 11-year-old sibling.

Finally, with growing dread, they reached the last bedroom, where a 4-year-old boy with knife wounds and a faint pulse was fighting for his life, ambulance workers said Saturday on Israel Radio. The medics worked frantically, but unsuccessfully, to resuscitate the toddler. One called it a scene of "incomprehensible horror."

The brutal killings Friday night of five Jewish settlers in the tightly guarded compound of Itamar, southeast of the West Bank city of Nablus, sent shockwaves through Israel, sparking worries of renewed violence in the Palestinian territories and heightening fears of retaliation from the Israel Defense Forces or angry settlers.

Israeli authorities suspect that the killings, the deadliest attack inside a settlement in several years, were either a strike by Palestinian militants or a revenge attack by residents of the West Bank village of Awarta, where two Palestinian teenagers were shot to death a year ago as they collected garbage near Itamar.

Israeli leaders condemned the attack on Udi and Ruth Fogel and three of their children and launched a massive manhunt throughout the region, setting up checkpoints, sealing off Palestinian villages, imposing curfews and conducting house-to-house searches, Palestinians said.

"Israel will not stand by idly after such a despicable murder and will act vigorously to safeguard the lives of the citizens of Israel and punish the murderers," Prime Minister Benjamin Netanyahu said Saturday.