Gaza always feels like a pressure cooker. How could it be anything else? It is one of the most overcrowded places in the world.
Hamas' deployment of its own security force has raised tensions
Getting on for a million and a half people live in a strip of land around 50km long and 9-12km wide.
But in this claustrophobic, fragile place, brutalised by getting on for 40 years of a violent Israeli occupation, the temperature is rising.
The heat has been turned up by a competition for power between Hamas and Fatah, the two main Palestinian factions, by the financial sanctions that have been imposed by Israel and the Western powers since Hamas came to power after January's election, and by the pressure that never goes away, which comes from the Israeli occupation.
You can feel the internal competition for power on every street corner.
Hamas has deployed its own force of armed men to act, they say, to uphold law and order.
They look highly disciplined, dressed in identical camouflage trousers, black tee-shirts and black baseball caps. They all have cropped hair, bushy beards and move like trained soldiers.
When they found themselves in a brief and almost bloodless shoot-out last weekend they took up firing positions and covered each other in ways that their rivals in Fatah often do not.
Fatah, Yasser Arafat's faction that is now led by the Palestinian Authority president Mahmoud Abbas, has been feeling the loss of office very sorely since Hamas won the parliamentary elections in January.
Fatah supporters see the new security force as provocation
Senior people in Fatah hope that the Hamas government is going to crumble sometime later this year. Fatah's men on the streets see the deployment of Hamas forces as a provocation.
"This is an ugly game," a young Palestinian soldier loyal to President Abbas said, as he eyed the Hamas men, with their beards and Kalashnikovs, on the other side of the street. "If this goes badly all of us could end up dead."
One senior Palestinian, highly respected in the West, told me the same thing. Gloomily, he said they were one serious incident away from an armed confrontation. He admitted that others were less pessimistic.
One is Ismail Haniya, the Palestinian prime minister from Hamas, who stood up in Gaza's oldest mosque last Friday and told the packed rows of the assembled faithful, as well as a much bigger audience across the Arab world live on al-Jazeera television, that there would not be a civil war, and that the difficulties that they are facing would not force the Hamas government to give up.
Palestinians ask whether it is right to collectively punish a people because of the way they voted in an election which the EU itself certified as democratic
He appealed to a sense of patriotism, asking why they would want to fight each other when the Israelis were "maintaining their settlements and occupation in the West Bank".
Armed Palestinian groups have had serious differences before. The presence of a common enemy in Israel, and the shared idea that they are all in the struggle together, has always held them back from the worst fratricidal strife.
But you cannot get away from the armed men on the streets, and the fact that the prospect of civil war comes up quickly in any discussion these days.
Mohammed Dahlan, once security chief in Gaza and still a powerful man who is talked about as a future Palestinian leader, told the BBC that he did not think it would come to civil war, because the interests of the nation would outweigh the interests of different groups.
He admitted though that all the Palestinian groups faced a challenge that had not been seen before.
The challenge is magnified enormously by the decision of the Americans, the European Union and Israel to do everything they can to stop money reaching the Palestinian Authority, because it is now controlled by Hamas, which they regard as a terrorist group.
The Palestinian Authority has not been able to create an independent state since it was established by the Oslo agreements 13 years ago, but it has created 165,000 or so jobs.
Each job pumps money into an extended family and through them into the local economy. The money has come into the PA from foreign aid, tax and customs revenues collected on its behalf by Israel and from bank loans, all of which have now been stopped.
Teachers and other public workers have not been paid since March
So since mid-March, the PA has not paid its staff, which means everyone from teachers to doctors to the men who clean the streets - and the men who carry the guns.
It does not help that most of the PA's uniformed, armed groups are loyal to Fatah, and are now not being paid by a Hamas government.
And, less visible than they were, but ever present in Palestinian lives in Gaza, are the Israelis.
Last Saturday the Israeli Defence Forces killed a senior member of Islamic Jihad, which unlike Hamas is not on a ceasefire, by firing a missile into his car.
They also killed three generations of the Amin family - a mother called Naimeh Amin, her seven-year-old son Mohannad, and the boy's grandmother Hannan - who happened to be passing in their car.
The dead woman's five-year-old daughter Mariyah and her uncle Maher were also in the car, and now lie in adjacent beds in the intensive care unit of Gaza's al-Shifa hospital.
Both were hit in the neck by shrapnel, and both are paralysed from the neck down, only able to breathe because they are on ventilators. The medical staff who are treating them work without pay.
The turbulence in Gaza holds big challenges, and not just for the Palestinians. Israel is set on its policy of freezing out Hamas and the PA. But will its interests be served if its pressure forces out an elected government or helps precipitate a Palestinian civil war?
Western governments, especially those in the European Union who have given big sums of money to the PA for more than 10 years, which hundreds of thousands of people now depend on, face a moral question as well.
Palestinians ask whether it is right to collectively punish a people because of the way they voted in an election which the EU itself certified as democratic.
Like it or not, what is happening amounts to collective punishment. Since financial sanctions were imposed hospitals are running low on drugs and even basic items like tape.
A drug company representative who did not want his name to be published told me that he could obtain what was needed easily, but only when the PA had the money to pay.
Medical services have been seriously hit by the funding freeze
Doctors say that people have started to die who otherwise should have lived, because they have not had the right drugs.
Patients with kidney failure, including small children, are getting dialysis twice a week instead of three times, and are developing complications that could shorten their lives.
I was shown a cancer patient who can no longer be treated in Israel, who lay in the hospital surrounded by his family waiting to die.
Work is being done by the UN, the EU and others to find ways of getting money to the Palestinians without giving it to Hamas-controlled ministries, and the Israel and the United States have promised a total of $20m (£10.6m) in medical aid.
But at al-Shifa hospital, the doctors said that none of it had reached them.