Aircraft clog airport in Port-au-Prince

Food, water and other aid flowed into Haiti in earnest on Saturday as relief groups and military personnel struggled with the capital's congested airport and damaged roads as they distributed aid to earthquake survivors.

Rescue efforts were briefly interrupted by a 4.5 magnitude aftershock. Searchers stopped working for about five minutes and then returned to searching for survivors trapped beneath the rubble.

Since Tuesday's 7.0 magnitude quake, Haiti's government alone has already recovered 20,000 bodies — not counting those recovered by independent agencies or relatives themselves, Prime Minister Jean-Max Bellerive said.

A final toll of 100,000 dead would "seem to be the minimum," he told The Associated Press. Other officials have estimated the toll could reach 200,000.

The UN mission chief in Haiti, Hedi Annabi of Tunisia, and his deputy, Brazilian Luiz Carlos da Costa, were among the dead, UN Secretary-General Ban Ki-moon announced Saturday.

Canadians have joined search and rescue efforts in full force. An Air Canada cargo plane left Montreal Saturday with doctors and supplies, including medicine and tents.

The relief flight to Port-au-Prince transported 100 search-and-rescue technicians from the Montreal police department, the Montreal fire department and Quebec provincial police to the badly damaged airport in Port-au-Prince, which is under U.S. control.

The Canadian military says about 1,000 troops from CFB Valcartier in Quebec are on standby for deployment to Haiti. Two Canadian warships loaded with supplies are inching their way to Haiti and are expected to arrive off the Haitian coast by Tuesday.

Meanwhile, a C-130 Hercules aircraft carrying Canadian evacuees arrived at Montreal's Trudeau International Airport on Saturday. A second such aircraft was to land later in the day, bringing the total number of Canadians ferried out of the country to 460 since Thursday.

"It's an extremely small airport [in Port-au-Prince]. There are planes circling and those on the ground are having a tough time getting out of there. There's not enough personnel to get the planes off the ground," said the CBC's Kristin Falcao from the Montreal hotel where evacuees who are not injured will be debriefed by the Red Cross.

The plan is to send two C-177 transport planes every day, with smaller C-130 Hercules aircraft making three flights every two days.

About 270 evacuees landed in Montreal early Friday. They were flown out of Haiti on Thursday on Canadian Forces flights. Most arrived with only the clothes they were wearing when the earthquake hit.

U.S. Homeland Security Secretary Janet Napolitano has asked Americans hoping to charter flights for independent relief flights to allow her department to co-ordinate aid efforts.

"That precious airspace is like gold right now," she told reporters at Homestead Air Force Base near Miami.

Thousands remain buried under the rubble of collapsed buildings, and thousands of decaying bodies are lying unclaimed in the streets. Thousands more have been burned or buried in mass graves.

The United Nations says it's feeding 8,000 people daily. About three million people have no access to food, water, and shelter.

The Haitian Embassy in Ottawa is scrambling to get aid to Haiti. The embassy's chargé d'affaires, Nathalie Gissel-Menos, says every minute counts.

"People are hungry, they are thirsty, they are in pain and they are desperate. The more time it takes for help to arrive, the more difficult it will be, because then you are facing the possibility of riots," she told CBC News.

There are still few signs that any aid is reaching people in much of the city, four days after the quake, amid growing concern that the desperate — or the criminal — are taking things into their own hands.

A water delivery truck driver said he was attacked in one of the city's slums. There were reports of isolated looting as young men walked through downtown with machetes, and robbers reportedly shot one man, whose body was then left on the street.

On Friday night, a group of Belgian doctors and nurses left a field hospital over security concerns, CNN reported. The medical team returned Saturday morning.