Also on board were one of Vichai’s two daughters, two pilots and a fifth person whose identity was not immediately known, the source said.
The helicopter crashed on Saturday just yards from the pitch in the club’s car park. Leicester had played a league match at home against West Ham United, drawing 1-1.
There were no confirmed details on whether anyone on board survived, the source said.
In Thailand, officials at King Power said they could not yet comment on the crash or say whether Vichai had been aboard when it spiralled out of control and crashed around an hour after the game. The club has not commented on that publicly.
According to witnesses, the helicopter just cleared the top of the stadium before it started to spin. It then plummeted to the ground and burst into flames.
Vichai, a father of four and the founder of duty-free giant King Power International, is a huge favourite with the fans after he bought the unfancied side from central England in 2010 and they went on to stun the soccer world by winning the Premier League title in 2016.