By Nidal al-Mughrabi
GAZA (Reuters) - An Israeli helicopter missile strike on a car in Gaza City killed top Hamas leader Abdel-Aziz al-Rantissi on Saturday, Hamas sources and medics said.

Witnesses said two of Rantissi's bodyguards were also killed in the attack in which two missiles were fired.

Medics said Rantissi, 56, Hamas's leader in the militant group's Gaza Strip stronghold, had been rushed to a Gaza City hospital in critical condition after the attack. Sources said he had been wounded in the head with shrapnel.

Hundreds of Hamas members and supporters flooded to the hospital after news of the Israeli raid.

A crowd of Palestinians swarmed around the wreck of the white car, pulling out what appeared to be fragments of clothing.

Hamas, which has been behind scores of suicide attacks against Israel in the 3 1/2-year old Palestinian uprising and has pledged to destroy the Jewish state, issued an immediate vow of revenge.

"Israel will regret this. Revenge is coming," said a senior Hamas leader at the hospital.

"This blood will not be wasted. It is our fate in Hamas and it is our fate as Palestinians to die as martyrs. The battle will not weaken our determination or break our will," Ismail Haniya told reporters.