ANFO of Shijiazhuang, China, on 16 March 2001. A total of 108 people were killed, and 38 others injured when, within a short time, several ANFO bombs exploded near four apartment buildings. Improvised bombs made with agricultural-grade AN are less sensitive and less efficient than the explosive-grade variety. In November 2009, a ban on ammonium sulfate, ammonium nitrate, and calcium ammonium nitrate fertilizers was imposed in the former Malakand Division – comprising the Upper Dir, Lower Dir, Swat, Chitral and Malakand districts of the North West Frontier Province (NWFP) of Pakistan – by the NWFP government, following reports that those chemicals
Improvised explosive device delays developed by IRA technicians could be set to accurately detonate a bomb weeks after it was hidden, which is what happened in the Brighton hotel bomb attack of 1984. Initially, bombs were detonated either by timer or by simple command wire. Later, bombs could be detonated by radio control. Initially, simple servos from radio-controlled aircraft were used to close the electrical circuit and supply power to the detonator. After the British developed jammers, IRA technicians introduced devices that required a sequence of pulsed radio codes to arm and detonate them. These were harder to jam. Roadside bombs were extensively