Nearby homes and businesses were evacuated around the intersection of Nashua Road and Mill Street. The Pepperell Senior Center, at 37 Nashua Road, was also evacuated as a precaution.

A Department of Public Works employee and a police officer on a detail suffered minor injuries and were treated at Nashoba Valley Medical Center in Ayer. They were released soon after, Deputy Fire Chief James Taplin said. Their names were unavailable.

Public-safety officials who were on scene described the odor of gas as "extremely strong." They said it could be smelled as far away as Main Street, a half-mile away.

"There was a big explosion. It was loud and debris was flying everywhere," said Police Capt. Michael Blood. "You could hear the high-powered hissing sound of the gas."

"We're very fortunate that no one was seriously injured in this accident," said Police Sgt. Todd Blain, noting that there were construction workers inside the hole at the time of the blast.

The workers were repairing a broken water main when they caused the accident, Taplin said. The town is in the midst of extending sewer lines from Nashua Road (Route 111) up to

Hollis Street (Route 122).

Evacuees with no place to go were cared for by the American Red Cross at the Doc Davis Ice Cream stand on Mill Street and Lomar Park, said Taplin.

By late afternoon, a faint scent of gas still lingered in the area of the accident, and roads leading directly to the Four Corners section of town were still closed.

Evacuated residents were allowed to return to their homes and roads were opened by evening.

National Grid workers were called to the scene and capped the broken pipe, later installing a temporary gas line as they repaired the main leak. Several lines to nearby homes were also shut off.