Police said one Uighur migrant was found hiding in a forest about 2 kilometres from the immigration office at about 9 pm on Wednesday.
Police found another Uighur hiding on the Mekong River bank in Mukdahan's Muang district, apparently waiting to find a boat to cross the river to Laos.
So far, three of the Uighurs have been captured and police are still searching for the remaining four.
The seven had been being detained at the Mukdahan immigration office since early 2016 for unlawful entry into the kingdom. The broke out of their detention room on Tuesday.