Gaza City, Gaza Strip ? Israel pounded more Hamas targets with airstrikes, killing 10 people and wounding dozens as it stepped deeper into fighting between the Islamic militants and the rival Fatah fighters of Palestinian President Mahmoud Abbas.

Palestinians gather around the rubble of a building Thursday after an Israeli airstrike on the facility, which was used by the Islamic group Hamas in Gaza City. Israel has threatened harsh action in response to repeated Palestinian rocket attacks.

The latest attack came early this morning as Israeli aircraft fired missiles east of Gaza City, killing four Palestinians, at least three of them Hamas militants, and wounding six people, Hamas and Palestinian doctors said. There was no immediate Israeli comment. Two other strikes followed but there was no word of any casualties, the doctors said.

The strikes, a series of Israeli attacks Thursday and the reported movement of a handful of tanks a few hundred yards into the northern Gaza Strip, followed days of Hamas rocket barrages into Israel.

Street fighting between the Palestinian factions that has gripped Gaza since the weekend calmed under a truce agreement, but clashes still killed at least four people – a day after 22 died in the worst battles during a year of factional bloodshed.

There was no sign of any Israeli military buildup that would indicate plans for a serious intervention into chaotic Gaza, though a few tanks and soldiers moved just across the Gaza border. Israel’s government said its attacks were intended solely to discourage rocket attacks on southern Israel.

“Israel will take every defensive measure to stop these rocket attacks. We will defend our citizens against the rockets, against the weapons, against the Iranian-backed Hamas who are attacking Israel,” government spokeswoman Miri Eisen said.

Analysts said Israeli policy makers were likely trying to walk a narrow line to avoid uniting Palestinian factions into a common front against Israel.

Hamas mounted accusations on its Web sites, radio and TV that Abbas-linked forces were working with Israel – a charge dismissed as “absurd” by a Fatah spokesman.

Although Israel said it wasn’t taking sides, the airstrikes did make it harder for Hamas gunmen to move around and that could help Fatah’s fighters, who appeared to have been outfought in the latest round of battles. Hamas fighters have clearly been more motivated in the current fighting and earlier battles in December.

In Washington, State Department spokesman Sean McCormack said Israel had shown “great restraint” in exercising its right to self defense and warned Hamas it would never achieve a Palestinian state unless it chose peace and worked with Fatah.

“They’re not going to see it by launching Qassam rockets into Israel. They’re not going to see it by attacking the legitimate security forces of the Palestinian Authority. They’re not going to see it by sending young people armed with suicide vests to blow up other Israeli youngsters,” McCormack said.