Israel warned its citizens in Egypt's Sinai Peninsula to evacuate immediately Saturday, hours after launching an airstrike that killed three Hamas militants accused of planning to abduct Israelis over the upcoming Jewish festival of Passover.

The government warned its citizens to "leave Sinai immediately and return to Israel," and quoted intelligence sources about "terrorist plans to kidnap Israelis and use them as bargaining chips."

The Sinai desert, with its pastoral coast, is a favorite vacation spot for Israelis despite periodic travel warnings. In October 2004, 34 people, most of them Israelis, were killed there when suicide bombers blew up the Taba Hilton Hotel.

Earlier Saturday, an Israeli military spokeswoman said an aircraft had fired at a squad of the Islamic militant group Hamas that "was planning to carry out kidnappings" during Passover, which begins later this month.

The group was planning to carry out the attacks in Israel and Sinai, she said.

Witnesses said a missile fired from an aircraft hit a car as it was traveling near Gaza City, Gaza Strip, just before 2 a.m. local time.

Gaza Health Ministry spokesman Adham Abu Salmia said three men were killed and another was injured.

Hamas later issued a statement saying the men killed were Hamas militants. They called the strike "a crime" and vowed revenge.

"We send a simple message to them (Israel): Don't try to test our patience, or you will open the gate of fire," said Hamas spokesman Abu Obeideh.

The armed wing of the Democratic Front for the Liberation of Palestine — a small group that rarely carries out attacks — announced Saturday it would no longer maintain a cease-fire with Israel.

After months of calm, Gaza militants barraged Israel with rocket and mortar attacks last month, and Israel's military retaliated with airstrikes. But last weekend, Hamas said it had no interest in a further escalation and urged militants in Gaza to hold their fire.

The Iranian-backed group has killed hundreds of Israelis in rocket attacks and suicide bombings. Israel, the U.S. and other countries consider Hamas a terror group because of their attacks aimed at civilians.

Gaza militants still hold captive an Israeli soldier, Sgt. Gilad Schalit, who was abducted in a cross-border raid in 2006.

Hamas is demanding the release of hundreds of Palestinian prisoners, including many convicted of murdering Israeli civilians, in exchange for Schalit. Hamas have banned the Red Cross from seeing Schalit and little is known about his condition.