From RT:

“We know that they were using this place to experiment with chemical weapons,” Iraqi special forces Brig. Gen. Haider Fadhil said.

The strength and potency of the chemical weapons that could be produced at the warehouse is still unknown, although, and despite the risk of contamination, Iraqi soldiers who entered the site for about ten minutes didn’t suffer any ill effects.

Earlier in January, troops involved in the liberation of Mosul University found that a dormitory there had been converted into a makeshift chemical weapons factory, using equipment and ingredients pilfered from the College of Sciences, including radioactive material. Specialists had to be called in to decontaminate the area.