Photographs of student victims of a Ukrainian passenger jet which crashed in Iran are seen during a vigil at University of Toronto student housing in Toronto, Ontario, Canada. Reuters

Bereaved friends and families joined in mourning after a Ukrainian airliner crashed near Tehran killing all 176 on board, as heartbreaking details started emerging about the victims, most of them from Iran and Canada.

According to Ukraine, 82 Iranians, 63 Canadians, 10 Swedes, four Afghans, three Germans and three Britons were on board, as well as 11 Ukrainians -- including nine crew.

About 30 came from the Iranian community around Edmonton, capital of Alberta province in western Canada, where resident Payman Parseyan described the tragedy as "devastating."

Relatives of the flight crew members of the Ukraine International Airlines Boeing 737-800 plane that crashed in Iran, mourn at a memorial at the Boryspil International airport outside Kiev. Reuters

"Every one of our community members was touched in one way or another," Parseyan told Canada's national broadcaster CBC.

Iran's supreme leader Ayatollah Ali Khamenei offered his "sincere condolences" to the bereaved families.

University professors, students, a newlywed couple: they are among the 63 Canadians lost when a Ukrainian plane crashed after takeoff in Tehran Wednesday, killing all 176 people on board.

"Everyone is shocked now," said Kavoss Zadeh, a resident of Toronto's Little Tehran neighbourhood.

The Iranian diaspora in North America counts a large portion of its population in Canada, with more than 210,000 Canadians of Iranian origin living in the country in 2016, according to official data.

Originally from Tehran, 65-year-old Zadeh has lived in Canada for 30 years and said he knew many of those killed in the crash.

A Boeing 737-800 of the Ukraine International airline is seen at the airport in Duesseldorf, Germany. File photo/AFP

"Some of them were dentists, doctors, highly educated people," said the supermarket owner. "When I heard in the morning, I was so sad."

The Ukraine International Airlines Boeing 737 disappeared from radar early Wednesday, just minutes after taking off from Imam Khomeini airport bound for Kiev.

Ukraine's Boryspil airport

At Ukraine's Boryspil airport, flowers and candles were laid out in front of portraits of the Ukrainian crew killed in the Boeing passenger jet crash in Iran on Wednesday.

One couple sobbed, covering their faces with their hands. Squatting down, several flight attendants arranged candles.

A woman places flowers at a memorial for the victims at the Boryspil airport outside Kiev. AFP

Dozens of people -- airline staff, passengers and locals -- gathered in the departure hall at the airport outside Kiev to pay their respects to the crew, five men and four women.

"I knew them all," said Artem, a Ukraine International Airlines pilot, who laid a bouquet of red roses by the portraits of his deceased colleagues.

He said he had met the entire crew before their departure for Tehran.

"They were very worried, had a bad feeling," he said.