A Canadian freelance photojournalist who was killed during an airstrike in Syria on Sunday is being remembered for his passion and devotion to bringing awareness to the conflict in the war-torn country.

Ali Mustafa and six others were killed when a Syrian government aircraft dropped barrel bombs in the rebel-held region of Aleppo, located in Syria鈥檚 north, according to activists in the region. They say the 29-year-old was standing with firefighters in the area when a bomb exploded nearby.

Mustafa鈥檚 sister, Justina Rosa Botelho, said she learned of his death when the activists sent her a photograph of her brother鈥檚 body.

Born in Toronto, Mustafa was the son of Pakistani and Portuguese parents who immigrated to Canada.

Botelho said in an interview with The Associated Press that Mustafa recently travelled to Syria from Turkey, and was expected to return to Toronto within a few weeks.

She said her brother worked tirelessly to document the tragedies occurring during the bloody civil war, which has been raging for nearly three years.

"He just wanted the world to know about human rights and all the horrible things going on down there," Botelho said. "He was passionate for the world to know."

Mustafa鈥檚 photographs have appeared in publications around the world, including The Guardian and on 麻豆影视 Channel.

Mustafa鈥檚 Friend Konstantin Kilibarda told 麻豆影视 Channel that the photographer 鈥渃ared about the world he lived in鈥� and was also involved in the Palestinian cause, Brazil and Egypt. In Canada, he worked on local anti-poverty matters.

鈥淗e believed in social justice, in humanity,鈥� Kilibarda said. 鈥淗e was a really caring, loving person.鈥�

In a May 2013 interview with News Channel, Mustafa said he felt it was important to do work in Syria in an effort to highlight the plight of Syrians. He said it was a 鈥渘atural outgrowth鈥� of his other work in the region.

鈥淚 think it was important to be there to tell the story as it was emerging as one of the mayor developing issues right now,鈥� he said at the time.

Mustafa also said journalists in Syria had to be aware of their surroundings and try to stay safe while capturing "as many quality photos as you can under those circumstances.鈥�

Even under constant threat of danger, Mustafa said Syrians were trying to have 鈥渟ome semblance of a normal life.鈥� He said they felt frustration and resentment toward the international community for what they called a lack of response to their suffering.

鈥淭hey felt that the world was ignoring them,鈥� he said.

Dozens of journalists have been killed in Syria since the war began three years ago. Syria is considered the world鈥檚 most dangerous place for reporters, particularly for freelance journalists as they often can鈥檛 access a news organization鈥檚 safety training, equipment or insurance.

Close to 100 people took part in a candle-light vigil to honour Mustafa near Yonge and Dundas Square Sunday evening.

Friends and colleagues gathered around candles and pictures of Mustafa as they remembered a man committed to social justice issues around the world.

Talal Kanaan, a close friend of Mustafa鈥檚, said he was a man passionate about fighting for human rights around the world.

鈥淗e wanted to stand for something that he believed in. He always stood for social justice, wherever that was,鈥� he told CP24 at the vigil.

鈥淚t鈥檚 something that is surely a tragedy for all of us.鈥�

鈥淲e knew that he was there, that he was doing very courageous work鈥t鈥檚 just a shock鈥� he said.

Others took to Twitter to pay their respects to the passionate social activist.