Hypochlorite + urea explosion

For my friends in the fertilizer industry, Dr Michael Fox has narrated an interesting incident where an explosion killed one person. The explosion occurred when 12.5% sodium hypochlorite was being unloaded into a tank that previously contained a liquid fertilizer consisting of 78% urea and sulfuric acid (1:1 ratio). His investigation found out that when "liquid fertilizer was added to an excess of sodium hypochlorite, an extremely vigorous reaction plus significant heat was generated. One possible explanation seemed that when there is excess of alkaline sodium hypochlorite, the sulfuric acid is neutralized and what remains is sodium hypochlorite and urea, a mixture said to produce explosive nitrogen trichloride "
Read about the incident in this link.