Tens of thousands of Palestinian civil servants have gone on strike in protest at the failure of the Hamas-led government to pay wages.
Most schools were closed on the first day of the academic year
There has been a big response in the West Bank, with most government offices shut and the first day of the school year heavily disrupted.
PM Ismail Haniya of Hamas had urged workers to boycott the strike.
An economic embargo on Hamas has left it unable to pay almost any civil servant salaries for six months.
The BBC's Alan Johnston in Ramallah says the strike is a key test for the Hamas-controlled administration.
He says the strike has powerful political overtones, with many government workers, particularly on the West Bank, linked to Hamas' rival, the opposition Fatah Party of President Mahmoud Abbas.
Palestinian police were out in many cities and towns to prevent clashes between Hamas and Fatah supporters.
On the West Bank almost nobody came to work in government ministries and some doctors said they were only dealing with emergencies, our correspondent says.
Bassam Zakarneh, head of the union organising the strike, said it had "succeeded by 95%".
"We have given many chances to the government but they have done nothing. Our demand is that we get our salaries and all our salaries, not partial salaries."
The embargo, enforced by Israel and the West because Hamas refuses to renounce violence or accept Israel's right to exist, has left the Palestinian government almost completely broke.
It has been able to pay its employees for only one of the past six months of work.
In the Hamas stronghold of the Gaza Strip, many government workers did go to their ministries, although most schools were closed.
Hamas government spokesman Ghazi Hamad said the strike was illegal.
"The measures will not lead to the lifting of the siege against our people and will not enhance the payment of salaries," he said. "On the contrary, they will increase the suffering."
Hamas Radio broadcast that the strike had failed in the West Bank and Gaza.
One student in Gaza City, Fadi al-Asali, 15, said: "I am going back home, and I hope this strike will be over soon because the losers are the Palestinians."