Bethel Volunteer Fire Department Chief Fred Ingram said the odor was first discovered around 9:30 a.m. in the Wine Lovers Shop at P.T. Barnum Square.

Ingram said the odor is coming from the brook that runs under the square, as well as under School Street. At a culvert near the Post Office, where the brook emerges, Ingram said, the odor was like gas and chlorine.

"We are thinking the odor of chlorine is coming from within the public water supply," Ingram said, because the water supply is treated with chlorine.

He said they believe there is a break in the water supply, where the stream is picking up a gas odor from ground that might have been contaminated by a former gas station.

"That's our theory at this time," Ingram said." We think the vapors are isolated to the one building at 23 P.T. Barnum, where the river runs under it."

The water is still safe to drink, he said. The area was not evacuated and there was no imminent danger to residents.

"But we're still monitoring," he added.