A twin-engine Army helicopter has crashed in Coonoor, Tamil Nadu. Chief of Defence Staff Bipin Rawat was on board the chopper. Three persons have been rescued so far. The three (identities not confirmed yet) are seriously injured and have been sent to Wellington Cantt Hospital. Poor weather is believed to have led to the accident. Rawat was attending a lecture in Ooty. His wife and a Brigadier-rank officer were with him, according to sources.