(AGI) Hanoi, July 7 - A military helicopter has crashed duringan exercise near the Vietnamese capital killing 19 people andleaving two seriously injured in hospital. The Russian-madeMI-171 with paratroopers on board took off from the Hoa Lacmilitary air base on Monday morning and immediately lostcontact with ground control. It crashed near a village 40 kmfrom Hanoi, the base second-in-command reports. The incident isthought to have been caused by mechanical failure and notsabotage. . .