A barrel bomb killed a Canadian photojournalist in Syria's Aleppo as he tried to document the death and destruction the controversial weapons caused in the city, reports said on Monday.
An official in the opposition-held part of the northern city said Ali Mustafa, a freelancer who sold pictures to the SIPA and EPA agencies, was killed on Sunday.
The opposition Aleppo Media Centre also reported the death.
"Four members of the (opposition) civil defence in Aleppo and 10 other civilians were killed, and dozens of others wounded, in a barrel bomb attack launched by helicopters against the Haydariyeh roundabout in the east of Aleppo city on Sunday morning," the centre said.
"A Canadian journalist, Ali Mustafa, was also killed... as he tried to document the massacre."
A media watchdog said Mustafa, 30, was killed when a barrel bomb went off as he tried to take photos of the destruction caused by the earlier bomb.
"Reporters Without Borders is dismayed to learn that Canadian freelance photographer Ali Mustafa was killed by a barrel bomb... while photographing the death and destruction caused by an earlier bomb," it said.
The Paris-based organisation said seven other people were killed.
The Syrian government has been accused of dropping barrels packed with explosives and scrap metal in a months-long campaign that has killed scores, mainly in residential areas of Aleppo.
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Canada's foreign ministry said it was aware of reports that one of its nationals had been killed in Syria.
Mustafa's sister, Justina Rosa Botelho, confirmed his death on her Facebook page, mourning her younger sibling.
"Hope the world will understand what an angel my brother was. He cared more for others than himself," she wrote.
Mustafa had worked in Syria periodically since early 2013, as well as in Israel and the Palestinian territories, Egypt and Brazil.
In an interview last year about his decision to cover Syria, the world's most dangerous conflict for journalists, he said he "could not ignore this ongoing human tragedy".
"Syrian people feel abandoned by the world. They are asking for our solidarity," he said.
Reporters Without Borders said Mustafa was the ninth foreign journalist to have been killed while covering the Syrian conflict.
Twenty-eight Syrian journalists and more than 100 citizen journalists have been killed in connection with their reporting during the past three years, it added.
Dozens more journalists have been kidnapped or jailed.
The conflict has killed more than 140,000 people since March 2011.