The military wing of Hamas said it fired rockets from Gaza into Israel on Saturday, a day after seven Palestinians died when Israeli artillery fired on a Gaza beach.

The Izzedine al Qassam group issued a leaflet in Gaza that said it shot seven rockets at Israel. Hamas,which holds political power in the Palestinian territories, does not recognize the state of Israel.

The Israeli military confirmed Saturday's attack from Gaza, saying 11 rockets had been launched into Israel. The military did not say who was responsible and reported no damage or injuries. Pieces of the rockets have not been found.

Izzedine al Qassam said Friday that its attacks on Israel, suspended since February 2005, would be renewed in the wake of a string of Israeli strikes -- including the artillery shell blast that killed at least seven Palestinians picnicking on a northern Gaza beach on Friday. (Watch the aftermath on the beach -- :46)

Palestinians said the picnickers were killed in shelling from a gunboat.

The killings sparked swift and sustained outrage in the Palestinian territories and elsewhere. Israel said it had believed the beach was empty.

Israeli Chief of General Staff Lt. Gen. Dan Halutz said the military was investigating the possibility that it was not naval artillery that struck the Palestinians.

The IDF said earlier it had been firing on rocket-launching areas in Gaza after a militant attack earlier in the day. The target areas were believed to be uninhabited, a representative said.

The Israeli daily newspaper Haaretz reported IDF had apologized for the beach killings, saying it "regretted the strike on innocents."

The paper quoted Palestinian Authority President Mahmoud Abbas as condemning the killings as a "bloody massacre." Abbas is from the Fatah party, which lost its power to Hamas in the Palestinian elections earlier this year.