Three army officers died when a Cheetah helicopter crashed inside the Sukna military base in West Bengal's Darjeeling district on Wednesday, a defence ministry spokesman said.
The crash occurred around 10.30 a.m. near the helipad inside the Sukna military base.
A junior commissioned officer was critically injured.
"It was a routine mission operating from Sukna and the crash happened when the chopper was coming in to land," the spokesman said.
An inquiry has been ordered.
Further details were awaited.
The Cheetah helicopter was returning after completing a reconnaissance flight from the forward area.