Gunmen who crossed from the Egyptian desert launched a series of attacks Thursday in southern Israel, killing eight people and threatening to destabilize a volatile border region that includes the Hamas-ruled Gaza Strip and the increasingly lawless Sinai Peninsula.
Israel blamed an armed Palestinian group from neighboring Gaza. Israeli forces killed five of the gunmen along the border with Egypt, the military said, and later launched an airstrike inside Gaza that killed five other militants from the same group as well as a child.
The Israeli military said three of the dead men in Gaza had been involved in planning the attack.
Gunfire continued on both sides of the border late into the evening. After nightfall, Israel's "Iron Dome" anti-missile system intercepted a rocket fired by Gaza militants at the city of Ashkelon, the military said.
The attacks were the deadliest against Israelis since a gunman killed eight civilians in Jerusalem in 2008. They suggested that Egypt's recent political upheaval and a resulting power vacuum in Sinai had allowed militants to open a new front against Israel on the long quiet border.
The attack began shortly after noon in southern Israel with gunfire targeting a civilian bus heading toward the Red Sea resort city of Eilat, at the height of the tourist season.
A number of passengers were hit, the military said. The gunmen had crossed the border and set up an ambush along a 300-yard strip; they were armed with automatic weapons, grenades and suicide bomb belts, according to the military.
"We heard a shot and saw a window explode. I didn't really understand what was happening at first," passenger Idan Kaner told Israel's Channel 2 TV. "After another shot, there was chaos in the bus, and everyone jumped on everyone else."
Within an hour, gunmen had riddled another passing bus and two cars with bullets and rigged a roadside bomb that detonated under an army Jeep rushing to the scene. At the same time, mortar gunners in Gaza opened fire at soldiers along the Gaza-Israel border fence.
TV video showed the first bus with its windows shattered. Its seats were stained with blood, and luggage littered the aisle.
The Israeli dead included six civilians and one soldier, according to the Israeli military's southern commander, Maj. Gen. Tal Russo.
Israeli soldiers eventually killed five attackers, the military said. Defense officials said three of the bodies were wired with explosives. It was not clear how many militants were involved or where they were from.
Egyptian security and Interior Ministry officials said a gunfight erupted on the border, and three Egyptians were killed -- one police officer and two soldiers.
During the fighting, the gunmen tried and failed to shoot down an Israeli helicopter with an anti-tank missile, according to the Israeli military.
Israel said the attackers had come from Gaza and made their way into neighboring Sinai and from there into Israel.
"Today we all witnessed an attempt to step up terror by attacking from Sinai. If anyone thinks Israel will live with that, he is mistaken," Prime Minister Benjamin Netanyahu said late Thursday.
U.S. Secretary of State Hillary Rodham Clinton condemned what she called "premeditated acts of terrorism against innocent civilians" and said the United States and Israel were "united in the fight against terror."