Initial findings suggest that Ammonium-Nitrate Fuel-Oil (ANFO) and detonators may have been used in Delhi car blast, NDTV reported. Ammonium nitrate is a white crystalline chemical commonly used as fertiliser and is not considered an explosive. When mixed with a fuel source like fuel oil, it forms ANFO, a powerful bulk industrial explosive. Its detonation velocity is about 3,200 meters/second.