AMHERST, Mass. — The strong smell caused by a man cooking urine has prompted the evacuation of an apartment building in Massachusetts.

Police responded to the Amherst apartment complex Wednesday afternoon after the manager found several unmarked glass containers containing liquids in an apartment.

Fire officials say the manager had received a complaint of a pungent odor.

Assistant Fire Chief Lindsay Stromgren says the smell came from urine and possibly other chemicals. She says it’s unclear what the man was trying to produce. He was identified, but hasn’t been criminally charged. A private cleanup company now has the chemicals.

The tenants were allowed back into their apartments after authorities determined Wednesday night that the substances weren’t explosive or a health hazard.