Up to 150 workers were believed to have been inside the factory, which produces syringes and other plastic medical supplies, at the time of the explosion.
The explosion did not happen when the plant was empty but when employees were there.
( z1 contrast :ARG1 ( z2 explode :polarity - :time ( z3 empty :ARG1 ( z4 plant ) ) ) :ARG2 ( z5 explode :time ( z6 employ :location z4 ) ) )