Israeli tanks moved and invaded Bethlehem early Friday, hours after Israeli forces blew up three Palestinian activists in the West Bank town and as the United States issued a plea for restraint. Israeli troops and Palestinian gunmen traded fire after 20 Israeli tanks penetrated deep into the autonomous Palestinian town, while two more Palestinians died elsewhere in the West Bank. Earlier, Palestinian gunmen shot dead an Israeli tourist and wounded several others, after three other Palestinians, including a schoolgirl, were killed yesterday by Israeli tank fire. Israeli troops killed a Palestinian policeman during clashes in the West Bank city of Ramallah. And a 13-year-old Palestinian boy died in the Gaza Strip when a live Israeli tank shell he was handling exploded. The deaths brought the toll from nearly 13 months of unrest to 887, including 687 Palestinians and 178 Israelis.