(VOVworld)- Prime Minister Nguyen Tan Dung has sent a message of condolences to his Lao counterpart Thongsing Thammavong after a Lao military helicopter crashed on July 27. In the message, PM Dung extended his deepest sympathy to the Party, State, Government, Army and people of Laos as well as the families of the deceased officials. The Mi-17 helicopter with four crew members and 19 passengers crashed in Luangphanxay village, Longchaeng district, Xaysomboun province en route from Vientiane to the northern provinces of Xieng Khuang and Huaphan, said the Lao Defence Ministry. An investigation is underway to find out the cause of the accident. Bad weather is predicted to the cause of the accident.