The convoy was guarded by about 100 police and Army officials who blocked off animal rights activists who got wind of the move.
Four of the elephants were flown away in an Antonov yesterday while the others are being kept in a small forest behind the airport, waiting for the next run.
The airport has been declared off-limits to outsiders until Thursday.
Animal welfare activists believe the elephants are from the wild, which would make their export a contravention of the Convention on International Trade in Endangered Species (Cites).
In June, a 25-hour blockade by wildlife activists and environmentalists in Kanchanaburi prevented these eight young elephants from being sent to Australian zoos. The protest cost the Australian zoos Bt40-50 million in plane charter costs. The blockade embarrassed the government, which has signed a contract with Australia to offer the animals in return for four koalas for Chiang Mai Zoo and four for the Night Safari, as well as other animals.
If it is established the young elephants are from the wild, the Antonov operator might come to be blacklisted, and his operations limited.
141 countries adhere to the convention, and ratified also to enforce sanction on tresspassers of the convention rules.