Foreign minister Livni says Israel may step up military action as gunbattles rage, trapping journalists inside a building in Gaza City. At least 23 Palestinians were killed on Wednesday (May 16) as Palestinian President Mahmoud Abbas's Fatah faction and Hamas battled for control of Gaza and Israel launched a deadly round of air strikes against the dominant Islamists. Palestinian officials said the widening hostilities could bring down a two-month-old unity government formed between Hamas and Fatah. Some Palestinians see this leading to all-out civil war and the end of the Palestinian Authority. Terrified Gaza residents hid indoors as masked gunmen fought running battles street-to-street, killing 16 people. At least 50 journalists were trapped in Gaza's main media centre. They said the building was surrounded by gunmen and some people inside had been injured. Footage of the trapped journalists, sitting on the floor in an attempt to avoid gun bullets and talking on cellphones, were aired on Al-Jazzeera International. Also on Wednesday, Israel's biggest air strike flattened a building used by Hamas's Executive Force in the southern Gaza town of Rafah, but military officials said the attack was not connected to internal clashes that have killed at least 40 people since Friday. A later air strike in northern Gaza killed another Hamas militant and wounded two other Palestinians, residents said. While battles raged throughout the Gaza Strip, militants have fired rockets at southern Israel, causing injuries but no deaths, in an apparent attempt to draw Israel into the fighting. Israel said the air strikes, the deadliest since a November truce in Gaza was declared, targeted a Rafah command centre used by Hamas to plan attacks and a rocket crew that had just fired into the Jewish state. Foreign Minister Tzipi Livni said Israel may step up military strikes in the Gaza Strip in response to a surge of Palestinian cross-border rocket salvoes. "It's important to understand that the Israeli government showed restraint in the last few months, but the last two days in which Israeli civilians are being attacked on a daily basis with missiles from Gaza strip, a place which Israel left in order to give the Palestinians the possibility to create normal life and not to attack Israel. This is a situation that should be changed, and the Israeli government will take all the necessary steps in order to bring security to the Israeli citizens," Livni told reporters after security consultations with Prime Minister Ehud Olmert and Defence Minister Amir Peretz. Israel faces a delicate balancing act. It is under heavy domestic pressure to stop the rockets and also wants Fatah to deal a blow to Hamas; it agreed to let 450 Fatah troops into Gaza from Egypt on Tuesday. Israel accepted four wounded Palestinians, including one girl, who were injured during the gunbattles and needed treatment in Israel. They were transferred from Gaza to Israel after dark and were taken to Israeli hospitals. But overt Israeli assistance for Fatah could backfire if Hamas is able to paint Abbas as an ally of the Jewish state, which many Palestinians see as their real enemy. Hamas and Fatah declared a ceasefire at 1700 GMT. But fierce gunfire and explosions could still be heard across the narrow coastal strip. In one clash, a Fatah security officer was killed and four others hurt. The sides traded blame on who shot first. Earlier, Hamas gunmen stormed the home of Abbas's top security chief, Rashid Abu Shbak, fired mortars at Abbas's compound and set fire to a building where the head of a pro-Fatah security service lives.