PORT-AU-PRINCE, Haiti - Under the shade of a maple tree, dazed and covered in dust, they gathered to marvel at how they managed to escape hell on earth in Haiti.

There was Martin Turgeon, a businessman from Quebec, one of about 50 Canadians gathered at the airport in quake-racked Port-au-Prince, waiting to board a military transport that would take him back to Montreal.

Just as he stepped into the bar at the Hotel Montana, he said, the ground began to shake.

"I had time to take five steps and then the ceiling collapsed," Turgeon said. There was a massive cloud of dust, then blindness.

"When it finally lifted, I realized the sixth floor had ended up in the basement," he said. "Fifteen seconds before or 15 seconds after and I wouldn't be here."

Turgeon's wife Nancy Savage was at Montreal's Trudeau international airport as she awaited her husband's return with about 150 other evacuess on two military aircraft that landed early Friday.

She was on the phone to Turgeon when the quake struck.

"He called right after the first shock and was talking to me when the second shock happened," Savage said.

"He's extremely tired, but he looks good," she said later after being reunited with her husband.

Christina Stewart was in Haiti scouting a missionary project for Vancouver-based charity Impact Nations. She had been working on her computer when suddenly the house she was in disintegrated around her.

"The floor opened up, the walls opened up," Stewart recalled as she waited to board the military plane in Port-au-Prince.

"The house was gone and I was alive."

The gathered 50 comprised the second wave of Canadians to be evacuated from the Caribbean nation's ruinous capital, memories of the carnage of Tuesday's magnitude-7 temblor still fresh in their minds.

At least five of them were injured, though believed to be in stable condition.

Stewart remembered spending that first night in a field that quickly became so crowded with people fleeing their homes there was nothing to do but stand.

When rumours of a tsunami - which later proved untrue - began to spread, everyone in the field starting running.

"We were just running through the streets, thinking the water was coming."

Canadian officials still have no clear idea about the extent of the damage. Some estimate there could be more than 50,000 dead, but Haitians could fare far worse in the days to come as the remaining supplies like food, water and fuel quickly dry up.

Dead bodies still litter the streets of Port-au-Prince and the Haitian government is offering money to anyone with a truck willing to cart them away.

Meanwhile, law enforcement officers are in the process of evaluating what could be an explosive security situation. Reports of looting circulated Thursday morning and there were concerns that damaged Haitian prisons have allowed hundreds of convicts to escape.

"The next 48 to 72 hours will be critical," said one Montreal police officer serving with the UN mission in Haiti who asked not be identified because he was not authorized to speak to the media.

"So far things have been relatively calm, but we're waiting to see how they'll react to food and water shortages."

Canadian officials have taken to travelling in armed convoys as a security precaution as they try get to people in need of help.

Earlier Thursday, Canada's first planeload of federal government aid touched down in Port-au-Prince, bearing an advance party for Canada's Disaster Assistance Response Team.

The big-bellied C-17 military transport disgorged some 40 Canadian Forces personnel to prepare for the main DART contingent, expected in the coming days.

An additional C-17 was not long behind, carrying provisions and supplies after departing from CFB Trenton, east of Toronto - a principal staging area for Canada's humanitarian effort.

The postage-stamp landing strip at the Port-au-Prince airport, largely spared from the devastation of the quake, was a hive of activity Thursday as help began pouring in from around the world.

Foreign Affairs Minister Lawrence Cannon said some 100 Canadians were seeking refuge at the Canadian embassy compound in Port-au-Prince, with 48 more being assisted by Canadian officials in the earthquake zone.

A pair of Canadian warships bearing humanitarian aid were also en route.

So far, four Canadians have been confirmed dead - an Ontario nurse, a Nova Scotia RCMP officer and a couple from Montreal are confirmed to be among the untold numbers of dead, while two RCMP officers and former Liberal MP Serge Marcil are among the missing.