Antonis Mavropoulos and Ahmed Khalid say they were supposed to be on Ethiopian Airlines Flight 302.

Mavropoulos, a nonprofit president from Greece, was on his way to a U.N. summit in Nairobi. Khalid was traveling from Dubai to Kenya’s capital, where his father was waiting.

Both were connecting in Addis Ababa and were late to their Ethiopian Airlines gate, they would later say in interviews.

The Boeing 737 Max 8, filled with 149 passengers and eight crew members, took off without them. Minutes later, it crashed — killing everyone on board.

In a Facebook post titled “My lucky day,” Mavropoulos said he learned of the crash as he waited to board a later flight. “The officer told me not to protest but to pray to God,” he wrote.

“I’m slowly coming to terms with what happened and how close it came,” Mavropoulos later told Skai TV in Nairobi. “On the other hand, I’m also very upset — I’m shattered — for those who were lost.”

10 ΜΑΡΤΙΟΥ 2019 - Η ΤΥΧΕΡΗ ΜΟΥ ΜΕΡΑ Τρέχοντας να προλάβω την πτήση ΕΤ 302 Αντίς Αμπέμπα - Ναϊρόμπι, που συνετρίβη 6...

Posted by Antonis Mavropoulos on Sunday, March 10, 2019

Ethiopia declared Monday a day of mourning as Red Cross workers picked through scattered plane debris outside Addis Ababa, where the aircraft left a charred crater. Authorities are investigating what went wrong, but officials said the senior pilot had issued a distress call shortly after the plane took off. The plane was cleared to return to the Addis Ababa airport but never made it.

The passengers and crew represented 35 countries, and many on board were aid and U.N. workers en route to the same U.N. environmental conference in Nairobi that Mavropoulos said he was scheduled to attend.

The Washington Post could not independently confirm the two men’s claims, and Ethiopian Airlines did not immediately respond to a request to verify their accounts. Mavropoulos and Khalid told their stories to multiple news organizations, including the BBC and the National.

In Kenya, Khalid’s father was waiting at the Nairobi airport for his son to arrive on his original flight when an airport security officer asked which flight he was expecting, the National reported.

“I answered him quickly because I wanted him to direct me to the arrivals, so I told him Ethiopia,” said Khalid Ali Abdulrahman, who was referred to as Khalid Bzambur in other news reports. “And then he said: ‘Sorry, that one has crashed.’ ”

The father said he was “shocked.”

But soon his son contacted him to say he was safe. Khalid’s flight out of Dubai had been delayed, which made him miss his connection to Nairobi on the ill-fated flight.

“When I reached Addis Ababa they told me to take the second flight, which is at 11 o’clock and I said it’s fine,” Khalid told the National.

Just before 11 a.m., the office of Ethiopia’s prime minister released the first official statement on the crash. About 30 minutes later, Ethiopian Airlines released its own statement.

On the plane, Khalid said he and his fellow passengers tried to learn more about the crash.

“Everyone was asking the cabin crew what was happening, but no one was saying anything,” Khalid said. “They were just going up and down until one of the passengers saw on his mobile that the first plane . . . like six minutes after it flew, it just crashed."

When Mavropoulos missed the Nairobi-bound flight by a few minutes, he said was initially angry because he felt nobody had helped him reach the gate on time, he wrote in his Facebook post. He was diverted to a later flight, he said, but wasn’t allowed to board that one, either.

Mavropoulos was led to a police station for questioning, he wrote in his post, because the plane had crashed and he was the only one scheduled to board who hadn’t.

That’s when the officer told him “not to protest but to pray to God.”

“I’m grateful to live and that I have so many friends that made me feel their love,” Mavropoulos wrote in his post, which included a photo of what appears to be his boarding pass.

An Ethiopian Airlines spokesman confirmed to the New York Times that Mavropoulos’s flight had been changed to depart from Addis Ababa later that afternoon.

On Monday, the U.N. environmental conference opened with flags flying at half-staff and a minute of silence for the victims. Nineteen U.N. staffers were on board the flight that crashed.

In a statement, the U.N. Environment Program said the crash was a “terrible loss” for the United Nations and the environmental community. The statement said the United Nations lost “staff, youth delegates travelling to the Assembly, seasoned scientists, members of academia and other partners.”

Kenya lost 32 residents, the most of any country. Eighteen Canadians and eight Americans were killed, as well as four or more citizens from Ethiopia, China, Italy, France, Britain, Egypt, Germany, India and Slovakia, the Associated Press reported.