By Rachel Harvey BBC correspondent in Gaza City

Last Tuesday night, three 14-year-old Palestinian schoolboys from the Gaza strip armed themselves with knives and crude homemade explosives and headed towards the Israeli settlement of Nezarim.

Their aim was to break through the heavily guarded security fencing of the settlement, but they did not even get close.

What happened in Jenin made us all angry and it pushes us to do something

Mohamad, Pupil at the school

Youssef Zaqout, Anwar Hamdouna and Ismail Abu Nadi were spotted by Israeli soldiers and shot dead.

The three boys knew their mission was probably going to end this way; they had left suicide notes for their families explaining their decision to seek "martyrdom".

At Salaha Edeen school where the three teenagers were studying, staff and pupils alike expressed their shock and anger.

"They were intelligent, active kids," the headmaster, Basil Alwahidi, told me, "and they go and do something like this".

Anger

One wall of the headmaster's office is taken up with wreaths of flowers, each sent with a message of condolence from other Gaza schools.

Hamas is trying to stop the trend to martyrdom

More wreaths now mark the empty desks where Ismail, Youssef and Anwar used to sit.

Mohamad used to sit next to Ismail Abu Nadi in class, now he sits alone.

"I had no idea he would do something like this," says Mohamad. "He was my friend. He used to say he wanted to be a doctor when he grew up - maybe a surgeon - but now he's dead.

"I think what happened in Jenin made him angry - it's made us all angry and it pushes us to do something".

Worrying trend

The problem is there is very little that 14-year-old boys can do. And perhaps it is that sense of powerlessness which is driving young Palestinians to such desperate, and ultimately futile gestures.

Maybe one day when I'm older, I too will become a martyr

Pupil

The worry now is that a trend may be developing, with other frustrated teenagers ready to try their hand.

The main Islamic militant group, Hamas, is so concerned about the situation that it has issued a statement calling on Palestinian children not to waste their precious blood.

"Too many young lives lost at the fences of Israeli settlements," the statement reads, "would be a catastrophe for the future of the Palestinian struggle."

Hamas has appealed to teachers and religious leaders to use their influence to persuade children that, rather than becoming young martyrs, they can help build a future Palestinian state by studying to becoming doctors, lawyers and engineers.

Temptation remains

Militant groups are not ruling out the possibility of more suicide missions in the future. But such operations, they say, should carried out by "properly trained" adults.

The question though is whether the call for restraint will be heard and understood by young Palestinians.

Back at Salaha Edeen school I asked the class of 14-year-old boys whether any of them were tempted to follow the example of their friends - Youssef, Ismail and Anwar.

My question was met with a long silence; then a shy boy, fiddling with the collar of his blue school uniform, spoke up.

"Maybe one day" he said, "when I'm older, I too will become a martyr."