A foul odor detected outside Lawrence Memorial Hospital early Tuesday morning remains a mystery, according to Lawrence-Douglas County Fire & Medical.

The hazardous materials unit and other fire units were called to the hospital at 12:34 a.m. An investigation initially led to some 55-gallon drums near the emergency room entrance, but the smell was determined not to be originating there, Division Chief Bill Stark said. The main entrance to the emergency room was closed for about an hour.

Fire investigators also checked the possibility that the smell was from a business where a chemical solvent had been used, but no final determination was made. The investigation continues, Stark said.