Palestinian Hamas spiritual leader Sheik Ahmed Yassin was killed early Monday in Israeli missile attacks, Hamas officials confirmed.  

Witnesses said Israeli Apache helicopters fired three missiles at Yassin and his two body guards as they left a mosque and killed them instantly.

Four people were killed and 12 wounded in the attack, witnesses said. Ambulances and fire trucks raced to the scene.

Thousands went out to the streets after news spread that Yassin was assassinated, shouting revenge, while hundreds of militants all over the Gaza Strip were firing in the air.

Hamas' military wing, the Ezzedin al-Qassam Brigades, vowed in a statement to avenge the killing of its spiritual leader Yassin with immediate reprisals.

"We, the Ezzedin al-Qassam leaders, have decided to take immediate reprisals, like an earthquake that will hit everywhere to destroy the Zionist presence," said the statement, adding that the response would be "unexpected."

"Words cannot describe the emotion of anger and hate inside ourhearts," said Hamas official Ismail Haniyeh, a close associate of Yassin.

The Hamas leadership said, "Sharon has opened the gates of hell. And nothing will stop us from cutting off his head."

Israel's Deputy Defense Minister Zeev Boim told public radio that "Sheikh Yassin deserved to die for all the terrorist attacks committed by Hamas."

Boim made the remark in the first reaction by the Israeli government to the killing of Yassin, who founded Hamas in 1987 and was held in Israeli prisons for several years before being released in 1994.

Following the assassination of the Hamas chief, Israel closed Erez crossing between Gaza Strip and Israel.

Profile: Yassin -- founder and spiritual leader of Hamas

EDS-Recast with more details and correction GAZA, March 22 (Xinhua) -- Palestinian Hamas spiritual leader Sheik Ahmed Yassin was killed early Monday in Israeli missile attack. Following is a profile of Yassin.

Yassin was a frail man who can barely see. His voice is thin and quavering.

He was born in 1936 in a Palestinian village called Al Joora near Ashkelon. Before the village was ruined by the Israeli army in 1948, Yassin and his family left the village and went to Gaza with thousands of Palestinian refugees.

Yassin, who now lives in a simple house in Sabra neighborhood in Gaza City, is quadriplegic in his wheelchair and suffers from pain in his eyes and ears. But he can speak.

When he was a young man, Yassin played in a gymnasium on the beach of Gaza, and his head and neck fell on the ground. Since then, young Yassin became physically paralyzed.

However, despite his disability, Yassin continued his education.

After finishing his education, Yassin worked as an Arabic teacher at a Palestinian elementary school. He was also an Imam of a mosque in Gaza City, where he became one of the most famous Palestinian mosque speakers in the Gaza Strip.

Later Yassin founded the movement of Al Mojama'a Al Islami (the Islamic Society), which was part of the Islamic Brotherhood movement.

In 1983, Yassin was arrested by Israel and sentenced to a 13-year imprisonment for hiding huge amounts of weapons, and for forming a military wing for the Brotherhood Muslims in the Gaza Strip with the aim of destructing the state of Israel.

Yassin was released in 1985 when Israel freed Palestinian prisoners in exchange for the releasing of Israeli hostages by the Palestinians.

By the beginning of the first Palestinian intifada (uprising) that began in December 1987, Yassin founded a new movement and called it the Islamic Resistance Movement (Hamas).

In August 1988, the Israeli army raided Yassin's house and threatened to deport him to south Lebanon.

In 1989, Israel again arrested Yassin with dozens of Hamas Movement members, accusing him of sending Hamas militants to kidnap and kill two Israeli soldiers.

In 1991 Yassin was sentenced to a life sentence, in addition to a 15-year imprisonment. All attempts to rescue Yassin and the interference of international human rights organizations had failed.

In the Israeli jail, Yassin became quadriplegic. He was released in October 1997, after Jordan exchanged him for the release of two intelligence agents of Israeli Mossad, who had tried to assassinate a leader of the Hamas Movement in Jordan.

Since then, Yassin led Hamas Movement. However, he is leading the political wing, not the armed wing of the movement, which was responsible for dozens of suicide bombing attacks as well as armed attacks in Israel.

In September last year, Yassin was lightly wounded in an Israeli missile attack in Gaza City. At the time, Yassin and Isma'el Haneya, a well-known Hamas leader, were having a meeting at the house of Marwan Abu Rass, another prominent Hamas leader, in Daraj neighborhood in Gaza City.

(Xinhua News Agency March 22, 2004)