For weeks the defining image of Israel’s military siege of the Gaza Strip was a distant haze of smoke rising from the ground, sanitised footage that told nothing of the horrors of war.

But in the late afternoon of January 16, Dr Izzeldin Abuelaish broke through the silence imposed by the Israeli government’s news blockade and for a few minutes the raw, unfathomable grief of a father whose three daughters and niece had been killed minutes before rang out to the world.

“My God, my God can’t anyone help us please,” the prominent Palestinian doctor said in a telephone interview with Israel’s Channel 10 station as he pleaded for an ambulance and an end to the shelling of his house.

Almost one year later Dr Abuelaish, 54, was reflective about the tragedy that symbolised the anguish of all Gazans during the 22-day offensive and earned him the nomination for the Nobel peace prize.

“It was a lesson, a message from God,” he said, speaking from his office in Toronto, where he has since moved with his surviving family.

“No one knew what was happening in Gaza, no one, no one. And this secret had to be disclosed, someone had to take this responsibility and someone had to take this message to the outside world. The responsibility fell on me.”

Dr Abuelaish, a widower, moved to Toronto last July with his two sons and three daughters to take up a position as associate professor of global health at the University of Toronto, one of the most prestigious institutions in North America.

His tranquil new life in the Canadian city is as far from Gaza as is possible to imagine. The doctor teaches graduate students, carries out research work on public health issues and in the evenings spends time with his children, whom he calls “my life, my everything”.

But he has not forgotten Gaza. In his spare time Dr Abuelaish has written a book about his experiences which is expected to be published next month by Random House. He also speaks to high school students and to Muslim and Jewish community centres, preaching a message of compassion and peace, its poignancy heightened by the fact that it is delivered by a man who watched the Israel Defence Forces kill his children.

“We must listen to each other, we must understand each other and use the right weapon, and I fully believe that words are stronger than hundreds of weapons. This is the new course we have to adopt,” he said.

“You must be angry but not just for anger itself. As a physician if I am angry about what is happening and thinking emotionally, I will never be a physician. I must be focused to treat the patient and to save his life. And that’s what we need. Palestinians deserve a better future and all of us must work to defend them not as Palestinians or Afghans or Iraqis or Africans, no, as human beings. Because humanity brings all of us together.”

Dr Abuelaish, born in the Jabalia refugee camp in Gaza, studied medicine at Cairo University in Egypt and earned a Master’s degree from Harvard University in America. He specialises in obstetrics-gynaecology and many of the texts he studied at home were written by Israeli doctors which is how he learnt Hebrew.

He was one of the few Gazans with a permit that allowed him to work in Israel and he travelled back and forth to the Chaim Sheba Medical Center in Tel Hashomer, just outside Tel Aviv, where he treated Arab and Israeli patients and did research work on fertility.

“I have been working in Israel for 15 years and have good relations with my colleagues. What we practise in the borders of the hospital why can’t our leaders practise that outside?”

When Operation Cast Lead began on December 27, 2008 he was at home in Jabalia with his eight children. His wife had died in September after a long battle with leukaemia.

There was no question of leaving the five-storey house which was known by everyone in the neighbourhood as belonging to the doctor. He said all his neighbours had fled but there was nowhere safe for civilians. The Israeli forces were hitting schools, hospitals and mosques in their offensive against Hamas.

Very little news was emerging from the scene of the fighting because Israel banned reporters from entering the territory. Dr Abuelaish was giving telephone interviews in Hebrew to Channel 10 news about the impact on Palestinian civilians. At 4.45pm he was scheduled to speak to Shlomi Eldar, one of the station’s correspondents, and had left his daughters Mayar, 15, and Aya, 13, in their bedroom on the third floor.

Seconds after he walked out of the room it was struck by a shell. Both girls were killed instantly. Bessan, 20, his eldest child ran to see what happened and a second shell hit the room. She was also killed. Their cousin, Nur, 17, also died.

“They were playing, they were speaking together and planning their future,” said Dr Abuelaish. Minutes later, he was on the phone with Mr Eldar, crying and begging for an ambulance. The visibly upset presenter promised to help and through his contacts got the army to stop firing at the doctor’s house and allow a Palestinian ambulance through. A fourth daughter Shatha, now 18, was badly injured by shrapnel.

Dr Abuelaish said he believed God saved his life for a greater purpose. The shells came just as he was due to speak to the journalist at a time when most Israelis were home for the Friday Shabbat dinner.

“If I waited two or three seconds in that room I would be gone. And the story would be finished. Why were my daughters tested? Why was I selected to survive? You know, God will test someone and whatever the burden of this test is he provides you with the equipment and the strength to face that tragedy. Everything from God must be good.”

That afternoon as he lay crying he looked to his son Mohammed, then aged 13.

“My son said to me, ‘My father, why are you upset? Why are you crying? You must be happy, you must be proud. My sisters are with my mum. My mum asked for them.’ I said I don’t need to worry if a child is telling me this. And I looked forward.”

Shortly before the military offensive began, the University of Toronto offered him a job, but he had been reluctant to take it because he did not want to leave Gaza. Israel declared a unilateral ceasefire the following day, on January 17, and soon after Dr Abuelaish decided to take the teaching position.

The Israeli army initially claimed snipers were firing from the doctor’s home and militants were inside the building. An investigation earlier this year found that the IDF fired accidentally on his house. The military said it was “saddened” by the harm it caused but under the circumstances the decision to fire shells on the building was “reasonable”.

“They said there were militants in my apartment. There were militants, my daughters were militants and they were armed with hope, love and education,” said Dr Abuelaish.

His surviving children are thriving in their new school including Shatha, who has recovered and is studying civil engineering in university and Mohammed, who is in high school. In memory of Aya, Bessan and Mayar the doctor launched the Daughters For Life foundation which will raise funds to educate poor Palestinian girls and provide them with health care.

“I could afford to help my children achieve what they wanted but there are many other girls especially in poor countries and they only have the right just to dream. So why not offer those girls a chance? Enlightened, healthy and educated women will raise healthy and educated children.”

Dr Abuelaish was nominated in April for the Nobel peace prize but lost to the American president, Barack Obama.

He plans to return to Gaza for good after his five-year work permit expires.

The territory is in ruins. The sea is poisoned by millions of gallons of raw sewage because water treatment plants are broken. The land is a rubble of stones and cement. Only 41 lorries of construction material have been allowed through since January. Gaza is becoming disconnected from the world as farms lay in waste and businesses shut down. The population is mostly young, traumatised and angry. The burden of responsibility to help Gaza is greater than ever for the doctor.

“No one can take me away from Gaza. I am not emmigrating to Canada. Now I am speaking with you and with my mind but my heart is with my people there. I go there to be energised. Gaza is my home, my childhood, it is everything. It’s the poor, it’s the suffering. It’s every moment. It is a paradise for me.”