VALHALLA, N.Y. (CBSNewYork/AP) — Hundreds of National Guardsmen from New York and New Jersey are undergoing training on how to respond to chemical, biological, radiological and nuclear attacks.

The four-day annual training evaluation began Friday at the Westchester County Fire Training Center in Valhalla.

Four hundred New York and 200 New Jersey soldiers and airmen are participating in exercises that simulate a train derailment chemical spill.