A jetliner carrying 157 people crashed shortly after takeoff from the Ethiopian capital Sunday, killing everyone aboard and carving a crater into the ground, authorities said. At least 35 nationalities were among the dead, including 18 Canadians.

It was not clear what caused the Ethiopian Airlines plane to go down in clear weather. The accident was strikingly similar to last year's crash of a Lion Air jet that plunged into the Java Sea, killing 189 people. Both crashes involved the Boeing 737 Max 8, and both happened minutes after the jets became airborne.

The Ethiopian pilot sent out a distress call and was given clearance to return to the airport, the airline's CEO told reporters.

At the crash site, the impact caused the plane to shatter into small pieces. Personal belongings and aircraft parts were strewn across the freshly churned earth. Bulldozers dug into the crater to pull out buried pieces of the jet.

Red Cross teams and others searched for human remains. In one photo, teams could be seen loading black plastic bags into trucks.

As sunset approached, crews were still searching for the plane's flight-data recorder, the airline's chief operating officer said.

Watch: People gather near ​Ethiopia plane crash site

People gather at the scene of the crash near Bishoftu, Ethiopia, where a search and rescue operation is underway. 0:58

Worried families gathered at the flight's destination, the airport in Nairobi, the capital of neighbouring Kenya.

Agnes Muilu said he came to pick up his brother. "I just pray that he is safe or he was not on it," he said.

Relatives were frustrated by the lack of word on loved ones.

"Why are they taking us round and round. It is all over the news that the plane crashed," said Edwin Ong'undi, who was waiting for his sister. "All we are asking for is information to know about their fate."

18 Canadians killed

The airline said 149 passengers and eight crew members were thought to be on the plane.

Ethiopian Airlines issued a list showing 35 nationalities among the dead, including 32 Kenyans and 18 Canadians.

Among the 18 Canadians killed were a Carleton University professor and a mother-daughter pair from Edmonton.

Canadian Prime Minister Justin Trudeau sent condolences via Twitter to the families of those lost in the crash. The government also provided a phone number for Canadians in Ethiopia to call for consular assistance.

Devastating news from Ethiopia this morning. Our thoughts are with all the victims on flight ET302, including the Canadians who were on board, and everyone who lost friends, family, or loved ones. Canadians in need of assistance, contact sos@international.gc.ca or 613-996-8885. —@JustinTrudeau

Canadian Foreign Affairs Minister Chrystia Freeland said on Twitter, "Terrible news from #Addis Ababa, #Ethiopia, this morning."

"My heartfelt condolences to all those who have lost loved ones. The Canadian government is in close contact with Ethiopian authorities to gather additional information as quickly as possible," Freeland said.

The list reflected a broad range of backgrounds, with passengers from China, the United States, Saudi Arabia, Nepal, Israel, India and Somalia. Several countries lost more than five citizens.

The World Food Program confirmed that two of the Italian victims worked for the Rome-based UN agency, while a Slovakian lawmaker said his wife, daughter and son were killed.

Some of those aboard were thought to be travelling to a major United Nations environmental meeting scheduled to start Monday in Nairobi.

The plane crashed six minutes after departing, plowing into the ground at Hejere near Bishoftu, or Debre Zeit, some 50 kilometres south of Addis Ababa, at 8:44 a.m.

The jetliner showed unstable vertical speed after takeoff, air traffic monitor Flightradar 24 said in a Twitter post.

The Addis Ababa-Nairobi route links East Africa's two largest economic powers and is popular with tourists making their way to safaris and other destinations. Sunburnt travellers and tour groups crowd the Addis Ababa airport's waiting areas, along with businesspeople from China and elsewhere.

Questions about airliner renewed

The accident is likely to renew questions about the 737 Max, the newest version of Boeing's popular single-aisle airliner.

Indonesian investigators have not determined a cause for the October crash, but days after the accident Boeing sent a notice to airlines that faulty information from a sensor could cause the plane to automatically point the nose down. The notice reminded pilots of the procedure for handling such a situation.

The Lion Air cockpit data recorder showed that the jet's airspeed indicator had malfunctioned on its last four flights, though the airline initially said problems with the aircraft had been fixed before it left the Indonesian capital of Jakarta.

"It's the latest iteration of the 737 line, which has been flying for many, many years, and has developed and gotten bigger with a longer range and more capacity," said Keith Mackey, a former airline pilot and president of a Florida-based aviation consultant firm.

"It's the latest and greatest version of the 737, and there's no reason to believe that there is anything wrong with the basic airplane that might have caused this," Mackey told CBC News.

Air Canada said it has offered its assistance in the investigation. The airline said it has operated the same type of passenger jet since 2017 and currently has 24 in its fleet.

The Boeing 737 Max 8 entered commercial use in 2017 and can carry up to 210 passengers. (Boeing)

"These aircraft have performed excellently from a safety, reliability and customer satisfaction perspective," an Air Canada spokesperson said in an emailed statement to CBC News.

WestJet said it has 13 of the Boeing 737 Max 8 in its fleet.

Safety experts cautioned against drawing too many comparisons between the two crashes until more is known about Sunday's disaster.

The Ethiopian Airlines CEO "stated there were no defects prior to the flight, so it is hard to see any parallels with the Lion Air crash yet," said Harro Ranter, founder of the Aviation Safety Network, which compiles information about accidents worldwide.

The airline published a photo showing its CEO standing in the wreckage.

Red cross team work amid debris at the plane crash site. (Michael Tewelde/AFP/Getty Images)

The Ethiopian plane was new, having been delivered to the airline in November.

State-owned Ethiopian Airlines is widely considered the best-managed airline in Africa and calls itself Africa's largest carrier. It has ambitions of becoming the gateway to the continent and is known as an early buyer of new aircraft.

"Ethiopian Airlines is one of the safest airlines in the world. At this stage we cannot rule out anything," CEO Tewolde Gebremariam said.

Last deadly crash in 2010

The jet's last maintenance was on Feb. 4, and it had flown just 1,200 hours. The pilot was a senior aviator, joining the airline in 2010, the CEO said.

Investigators were securing the crash site and collecting evidence. (Tiksa Negeri/Reuters )

The last deadly crash of an Ethiopian Airlines passenger flight was in 2010, when a plane went down minutes after takeoff from Beirut, killing all 90 people on board.

African air travel, long troubled and chaotic, has improved in recent years, with the International Air Transport Association in November noting "two years free of any fatalities on any aircraft type."

Ethiopian officials declared Monday a national day of mourning.

A family member of a victim involved in Sunday's plane crash talks on a cellphone at Addis Ababa international airport. (Mulugeta Ayene/Associated Press)

Sunday's crash comes as the country's reformist prime minister, Abiy Ahmed, has vowed to open up the airline and other sectors to foreign investment in a major transformation of the state-centred economy.

Ethiopian Airlines' expansion has included the recent opening of a route to Moscow and the inauguration in January of a new passenger terminal in Addis Ababa to triple capacity.

Speaking at the inauguration, the prime minister challenged the airline to build a new "Airport City" terminal in Bishoftu — where Sunday's crash occurred.