This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

WHEAT RIDGE, Colo. — Two people were taken to a hospital because of an unknown odor late Thursday night, the Arvada Fire District said.

On Friday morning, homes and an RV park near the 4400 block of Simms Street in Wheat Ridge were evacuated as a civil support team from Buckley Air Force Base was brought in to determine the cause of the odor.

Reverse emergency notification calls were also issued for a 14-block radius. West 44th Avenue was closed between Robb and Tabor streets for the investigation.

Firefighters first were called to the neighborhood about 9:45 p.m.

Firefighters found the odor was contained to a neighbor’s pool shed, but they could not determine the cause or what it was.

Homes in the neighborhood were evacuated, but all but one family was allowed to return overnight.

Two people were taken to a hospital to be treated for inhalation. Their conditions are not known.

Officials said the odor disappeared about 2 p.m. Friday. All evacuees were allowed to return home and the roads reopened.

Firefighters were unable to determine what the odor was.