Palestinian gunmen linked to the former governing Fatah party have stormed the compound in Gaza which houses the Finance and Foreign Ministries.
The gunmen, who are members of the al-Aqsa Martyrs Brigades, opened fire on Palestinian security forces. At least seven people were injured in the fresh wave of violence.
The militants were demanding jobs in the security forces.
In a separate development, the Israeli authorities decided to partially reopen the main trade crossing into the Gaza Strip after the United Nations warned of a looming humanitarian crisis as a result of food shortages.
A spokesman for the defence ministry in Tel Aviv said the Karni crossing in central Gaza, which has been closed for most of the year, was reopened on a temporary basis to allow aid to be brought into the territory.
An Israeli army spokeswoman said the crossing was open for two hours before being shut again because of a security alert.
The move came after talks yesterday hosted by the US ambassador to Tel Aviv where the Palestinians pressed for the reopening of Karni.
The UN agency for Palestinian refugees also warned that the residents of Gaza were running dangerously short of basic foodstuffs, including bread and sugar.
Israel had previously offered to channel aid through another border crossing in the south of the territory, known as Kerem Shalom, but the idea had been resisted by the Palestinians who insisted that Karni be reopened.
