-The Howe Avenue building that houses the Subway sandwich shop and Cigarella cigar shop is fully evacuated due to a suspected natural gas leak, as of Friday night.

Crews from Yankee Gas (now known as Eversource Energy) are digging a few feet outside the building, searching for the source of the probable leak. “They have to find it and remedy it,” said Shelton Fire Chief Fran Jones.

All power has been turned off in the building, and residents in the upper-floor apartments may have to seek other accommodations for tonight. Some of these residents have been keeping warm at the nearby Echo Hose firehouse.

A contingent of Shelton firefighters is keeping watch near the scene, ready to provide any needed assistance. “We could be here all night,” said one firefighter.

Two gas leak complaints

Jones, who has been at the scene, said two separate gas leak complaints were received earlier in the day.

At about 10:45 a.m., someone walked into the Echo Hose firehouse and said they had smelled gas at 375 Coram Ave., a small one-story structure that houses a law office. The building is between the U.S. post office and firehouse.

Firefighters checked the area with their hand-held gas detection meters and determined gas was present, and contacted Yankee Gas, who sent personnel to look further into the matter.

“Significant amount’

A while later, a smell-of-gas complaint came from someone at the Cigarella cigar shop. Gas detection meters used by Yankee Gas employees, who by then were in the area due to the other complaint, and firefighters again found there was natural gas present.

“We found a significant amount of gas in Cigarella,” Jones said.

On a scale used to determine the potential seriousness of a leak, Jones said a 20% reading means people must be evacuated. The reading inside Cigarella was 60%.

Firefighters then proceeded to get people out of the building.

Nearby buildings not affected

Readings are not high in nearby buildings, and they remain occupied. This includes the post office, the adjacent building that houses H&R Block, the Pierpont Building (including Amici's Restaurant, which is open), and the Echo Hose firehouse.

Readings inside the law office also were determined to be low enough to allow it to be occupied.

Yankee Gas crews now are concentrating on a spot just outside Subway, on the section of Bridge Street that connects Howe Avenue with the U.S. post office parking lot. They are using a small backhoe to assist in the process.

The ground is frozen due to the cold weather, which makes the digging more of a challenge.

But workers also are checking for leaks elsewhere in the area, closer to the post office. Earlier, they checked manholes on Coram Avenue and marked areas with orange spray paint in the sidewalk area.

Are the leaks related?

Jones said the two leaks may be related because of natural gas “chases,” which involves leaking gas moving through pipes in an area to follow paths of least resistance.

This may be particularly true in the winter, because leaking gas may have trouble passing through frozen ground.

The Subway is at 462 Howe Ave., and Cigarella is at 464 Howe Ave.