About 20 people were believed to be on board the air force plane that left Vientiane, Laos' capital, early Saturday morning to bring the group to an official ceremony in the northeastern province of Xiangkhoung, about 470 kilometers (290 miles) away, said Thai Foreign Ministry spokesman Sek Wannamethee.
The Russian-made Antonov AN-7KTK300 crashed in the Pek district of Xiangkhoung province, where authorities were "helping to rescue the survivors," according to Lao news agency KPL, which cited an announcement from the Prime Minister's Office. The report did not say how many people died in the crash or survived.
Among those confirmed killed were Defense Minister Douangchay Phichit and his wife, said Nipat Thonglek, the Thai defense ministry's permanent secretary.
Douangchay was also one of the country's deputy prime ministers and a high-ranking member of Laos' Politburo, the main decision-making body for the authoritarian nation's ruling Communist Party.
Other fatalities included the governor of Vientiane, Sukhan Mahalad, and two other senior officials, Nipat said. He said he was given the information by authorities in neighboring Laos who did not immediately release details of the other passengers.
The cause of the crash was not immediately known.
Lao National Television showed images of the mangled wreckage in a forested area with smoke rising from its badly charred remains. The footage showed rescuers pulling away pieces of debris and trying to dig into the fuselage with shovels, as medical crews stood by watching.
The site of the crash was not far from one of Laos' major archaeological sites, the Plain of Jars, located in Xiangkhoung province, which borders northwestern Vietnam.
In October, a Lao Airlines ATR-72 turboprop crashed during a heavy storm as it approached Pakse Airport in southern Laos, killing all 49 people on board.
Associated Press writer Jocelyn Gecker contributed to this report.
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