Hundreds of Fatah gunmen stormed Hamas-controlled institutions in the West Bank, including parliament and government ministries on Saturday, international media reported.
The gunmen told the staff that those with ties to Hamas will not be allowed to return.
The Fatah supporters chanted "Hamas Out" then climbed on the roof of the building and fired in the air. They also tried to seize the deputy speaker, but were stopped by employees. Other Fatah activists took over the Education Ministry and the Prime Minister's Office.
Many government employees tied to Hamas had not showed up for work on Saturday, the start of the work week in the West Bank, after Hamas took control of Gaza in a military campaign.
A member of the Al Aqsa Martyrs' Brigades, a violent offshoot of Fatah, said his group planned to take control of all Hamas institutions, in response to Hamas' takeover of Gaza.
The West Bank, home to most of the Palestinian population, is dominated by the more moderate Fatah, which has ties to Israel and the West.
Gaza is now under the control of Hamas, an Islamic movement with close ties to Syria and Iran.