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’s 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’s sister, Justina Rosa Botelho, said she learned of his death when the activists sent her a photograph of her brother’s 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’s photographs have appeared in publications around the world, including The Guardian and on CTV News Channel.

Mustafa’s Friend Konstantin Kilibarda told CTV News Channel that the photographer “cared about the world he lived in” and was also involved in the Palestinian cause, Brazil and Egypt. In Canada, he worked on local anti-poverty matters.

“He believed in social justice, in humanity,” Kilibarda said. “He was a really caring, loving person.”

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 “natural outgrowth” of his other work in the region.

“I think it was important to be there to tell the story as it was emerging as one of the mayor developing issues right now,” 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.”

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

“They felt that the world was ignoring them,” he said.

Dozens of journalists have been killed in Syria since the war began three years ago. Syria is considered the world’s most dangerous place for reporters, particularly for freelance journalists as they often can’t access a news organization’s 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’s, said he was a man passionate about fighting for human rights around the world.

“He wanted to stand for something that he believed in. He always stood for social justice, wherever that was,” he told CP24 at the vigil.

“It’s something that is surely a tragedy for all of us.”

“We knew that he was there, that he was doing very courageous work…it’s just a shock” he said.

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