RAMALLAH, West Bank -- A crowd estimated at 30,000 gathered in the West Bank self-rule city of Ramallah Friday for the funeral of four Palestinian security officers killed by Israeli troops.

Angry mourners shot into the air and shouted for revenge.

The four being buried were among the 13 Palestinians killed during an Israeli army incursion, which saw the town almost completely occupied over the last three days, AFP reported.

The Israeli army announced Friday it had pulled out of Ramallah, as well as from other towns in the West Bank and Gaza Strip, after rolling in as part of Israel's largest military operation in the West Bank or Gaza Strip since 1967.

The withdrawal came after heavy U.S. pressure on the army to end its occupation of Ramallah with the arrival of U.S. peace envoy Anthony Zinni in Israel.

In the West Bank town of Bethlehem, thousands of angry mourners, many waving Palestinian flags, attended the funeral of Ahmad Noman, 37, the director of a hospital in nearby Al-Khader.

He was killed a week ago by machinegun fire from an Israeli tank outside Bethlehem as he was bringing in medical supplies in his car.

Palestinian security sources said he had received permission from the Israelis to make the journey when he was shot.

Meanwhile, Palestinian President Yasser Arafat dismissed a phased Israeli troop withdrawal from the West Bank city of Ramallah as a trick.

Israeli troops started leaving Ramallah on Thursday evening, three days after they entered the Palestinians' main commercial and political hub in the West Bank and shortly after U.S. envoy Anthony Zinni began a new peace mission to the Middle East.

"They want to finish the occupation of all our towns and cities and villages...before Zinni's arrival, and also as nothing more than a trick for their propaganda," Arafat told Reuters in an interview on Thursday night at his Ramallah Headquarters.

"As you see, you are here and you can see their tanks everywhere in this city," he said.

Tanks remained outside his headquarters and in other parts of Ramallah as he spoke. The withdrawal ordered by Israeli prime minister Ariel Sharon was expected to be gradual.

Arafat sounded defiant and confident at his headquarters as he sat in front of a Palestinian flag and a picture of the dome of the rock mosque in Bethlehem's old city -- a symbol of the 17-month-old Palestinian "Intifada" for independence.