As per news reports, a brine unit chiller with ammonia exploded on Saturday i.e 28.06.2014, leading to ammonia leak, injuring 10 persons with burns. As per some other reports, 11 persons got injured in the incident. Persons suffered suffocation, breathlessness and giddiness.
To clear the choking of brine in the chilling unit, steam was admitted which led to expansion of ammonia (anhydrous?) and pressure rise that causing explosion.
As per reports in some other news papers, use of steam instead of hot water led pressure rise. Hot water use limits the temperature compared to steam and may be this is one of the reasons for the incident.
Reports indicating fire extinguished rise questions of whether it is ammonia fire or any other fire.
http://www.newindianexpress.com/states/andhra_pradesh/11-Hurt-in-Pharma-Unit-Blast-3-Critical/2014/06/29/article2306006.ece
http://www.thehindu.com/todays-paper/10-injured-in-blast-at-drug-unit/article6158709.ece