Israeli jets attacked the southern Gaza Strip Thursday after the government blamed Gaza militants for a series of deadly raids in southern Israel.

Israeli military officials say at least five people were killed in the airstrike. The Reuters news agency says the dead included a chief of the Popular Resistance Committee, an armed Palestinian faction.

Earlier Thursday, gunmen carried out a series of apparently coordinated attacks in southern Israel that killed at least seven people.

Israeli officials say the attacks took place in quick succession near the border with Egypt's Sinai Peninsula. They say say 40 people were wounded in the attacks.

Authorities say gunmen opened fire on a passenger bus and a private vehicle, targeted a military patrol and detonated explosives near security forces. Israeli media reports say Israeli troops tracked and killed seven suspected attackers.

Defense Secretary Ehud Barak called the attacks a grave terrorist incident. Barak and other Israeli officials asserted that the attackers came from the Hamas-ruled Gaza Strip and entered Israel from the Sinai. Hamas has denied involvement.

The United States and the United Nations issued separate statements condemning the attacks. U.N. chief Ban Ki-moon also urged restraint.

Israel has expressed concern about a deterioration of security in the Sinai since Egypt's President Hosni Mubarak resigned in February.

Last week, Egypt moved additional forces to the region in an effort to improve security.