The 176 victims onboard the Ukraine International Airlines flight that crashed after takeoff from Tehran on Wednesday hailed from various countries.
They included 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, four Afghans, three Germans and three British nationals, according to a tweet from Ukrainian Foreign Minister Vadym Prystaiko.
Canadian Prime Minister Justin Trudeau said 138 of the passengers were going to fly on to Canada, and that their connecting flight had arrived in Toronto with many seats empty.
The victims included a newlywed couple, a family of four, a mother and her daughters, "bright students and dedicated faculty members," Trudeau said.
"Canadians have questions and they deserve answers."
Among those known to have perished was Mehdi Eshaghian, who had previously studied at Sharif University of Technology in Tehran.
School friend Ali Mazaheri told CNN that Eshaghian had moved to Canada in 2018 to embark on a postgraduate degree, but had been back to Iran to visit family.
Speaking soon after news of the crash broke, Mazaheri told CNN: "We are all sad. I was crying from the morning. He was going to be 25 in a week. He was kind, humble, caring."
The pair had been friends for about a decade since meeting in their second year at Safi High School in Ishafan, where he still lives, Mazaheri said.
Eshaghian had embarked on a masters degree at McMaster Automotive Resource Center (MARC) in September 2018, according to his friend. "He then changed his program to PhD on his teacher's advice," Mazaheri said. "He was happy in Canada."
A tweet from Sharif University suggested that a further 12 former students were among the dead, but their identities are yet to be confirmed.
Three Britons are known to have died in the crash. One of them, Saeed Tahmasebi Khademasadi, 35, was a PhD student at Imperial College London, while also working as an engineer for Laing O'Rourke.
In a statement released to CNN, Imperial College said: "We are deeply saddened at this tragic news. Saeed Tahmasebi Khademasadi was a brilliant engineer with a bright future. His contributions to systems engineering earned respect from everyone who dealt with him and will benefit society for years to come. He was a warm, humble and generous colleague and close friend to many in our community. Our thoughts and sincere condolences are with Saeed's family, friends and colleagues, as well as all those affected by this tragedy."
Sam Zokaei, who was on holiday in Iran, also died in the crash. The British passport holder was a reservoir engineer for BP, based at the company's site in Sunbury-on-Thames, west of London.
A spokesman for BP told CNN: "With the deepest regret, we can confirm that one of our colleagues at BP, Sam Zokaei, was a passenger on the Ukrainian International Airlines plane that crashed in Iran this morning, reportedly with no survivors.
"We are shocked and deeply saddened by this tragic loss of our friend and colleague and all of our thoughts are with his family and friends."
A spokesperson for the airline told a press conference that the plane was last checked on January 6 and there have been no complaints previously in relation to the jet.
Yevhenii Dykhne, president of Ukraine International Airlines, said that most of the dead passengers were in transit to Ukraine to connect to further flights, he said.
A spokesman for the UK's Foreign & Commonwealth Office said: "We are deeply saddened by the loss of life in the plane crash in Iran overnight. We are urgently seeking confirmation about how many British nationals were on board and will do all we can to support any families affected."
Some of the dead were apparently students at the Sharif University of Technology Association in Tehran. Siamak Aram, a board member of SUTA, told CNN: "Yes, unfortunately at least 14 Sharif alumni died."
A spokesperson for the German Foreign Office said: "The Federal Foreign Office and our Embassy in Tehran are in close contact with the relevant authorities to determine whether there were German citizens aboard the aircraft."
Foreign minister Heiko Maas tweeted: "We are deeply saddened to learn of the tragic crash of flight #PS752 that was headed from Tehran to Kyiv. At this difficult time, our thoughts go out to the friends & families of the victims."
Meanwhile, a spokesman for Sweden's Ministry of Foreign Affairs (MFA) urged worried relatives to get in touch. He told CNN: "A number of Swedes have lost their lives in the aircraft crash in Iran. We are now working intensively to obtain clarity about the number of Swedes who have died."
The spokesman said it is doing this "onsite in Iran, through our embassy and at the MFA in Stockholm."
He added: "The MFA has decided to activate its crisis management organization until further notice. We urge worried relatives to call the MFA on +46 8 405 92 00. We urge Swedes in Iran to contact their relatives."