At least seven people have been killed in a series of apparently coordinated attacks in southern Israel.
Reports suggest a bus travelling along a highway on the Israel-Egypt border was attacked by gunmen, while other attacks on an Israeli military patrol and a passenger vehicle, were also reported, all of which took place near the resort city of Eilat, towards the border with Egypt's Sinai Peninsula.
Reports of a fourth attack by gunmen were not immediately confirmed by officials.
According to the Israeli military website, the bus was travelling from Be'er Sheva to Eilat when it came under attack. Officials blamed "terrorists" for unleashing violence against both civilians and soldiers.
"We are talking about a terror squad that infiltrated into Israel," Israeli military spokesperson Lt. Col. Avital Leibovich said Thursday.
"This is a combined terrorist attack against Israelis."
Israeli Defence Minister Ehud Barak said Thursday's violence raises concerns about the insecurity that exists in the Egyptian Sinai Peninsula and claimed terrorists were behind the incidents and asserted that the source was the Hamas-ruled Gaza Strip, but no one has yet claimed responsibility for the assault.
"The incident underscores the weak Egyptian hold on Sinai and the broadening of the activities of the terrorists," Barak said in a statement.
"The real source of the terror is in Gaza and we will act against them with full force and determination."
CTV's Middle East Bureau Chief Martin Seemungal said the bus appears to have been primarily carrying soldiers when it came under attack.
"The road that they were travelling along goes right along the Egyptian border and from what we understand there was a car that drove by the bus, it was kind of a drive-by shooting," Seemungal told CTV's Canada AM from Eilat, Israel.
"They got out of the car, they fired on the bus and several people were injured."
Meanwhile Israel's Haaretz newspaper reported that the soldiers on the bus were leaving their bases for the weekend.
Military spokesperson Brig.-Gen. Yoav Mordechai said Thursday's attacks were well-planned and authorities have not yet managed to track down the assailants.
But one Sinai-based official denied suggestions that the assailants involved in Thursday's attack crossed the border from Egypt or fired their weapons from Egyptian soil.
"The border is heavily guarded," the official told The Associated Press, speaking on condition of anonymity.
Egypt recently moved thousands of troops into the Sinai Peninsula as militants have become increasingly active since Mubarak was ousted and they had previously been accused of attacking police patrols and bombings a pipeline that brings oil to Israel and Jordan.