Officials said four people were taken to Frederick Memorial Hospital with respiratory issues after being inside the building.
Captain Kevin Fox of Frederick County Fire and Rescue said crews initially believed the incident inside the Righttime Medical Care building was a gas leak, but after reading meters, they instead suspected some type of a sewer gas leak.
He said crews were on the scene trying to determine the exact cause of the issues, but said the problem is contained to the one building.
As of 10 p.m. Monday night, emergency officials had cleared the scene, and deemed the building safe.
No update on the condition of the people who were taken to the hospital was available.
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