Work crews ruptured a 4-inch natural gas main line Tuesday morning forcing the evacuation of 150 Musco Lighting and MCG employees in the 100 block of First Avenue West.

Oskaloosa Fire Department Capt. Mark Neff said work crews with Dugger Construction were excavating on the west side of the building when the break occurred. He said where the crew was digging was not where the break occurred.

“They were digging in one area, and what they hit was a footing from an old building and it shook it and it broke a line over here,” Neff said. “It wasn’t exactly where they were digging. Because it was a separate line from what they were digging that went.”

Neff estimated the break in the gas line was 20 to 25 feet away at an angle from where the actual digging was taking place. He said the gas service line was approximately 5 feet deep.

Mark Reinders, MidAmerican Energy communications manager, said the break was detected around 11:30 a.m. and squeezed off by 12:30 p.m. He said no customers were impacted by the break.

Reinders said the contractor was doing private sewer work in the area when the 4-inch main ruptured.

Neff said the fire department was notified of the break at 11:27 a.m. and was in service for approximately one hour. They responded with four personnel and three units and sealed off the parking lots.

“We sealed off the area so they could get their work done,” Neff said.

Employees were allowed back into the building around 12:30 p.m., he said.

Herald City Editor Michael Schaffer can be reached by email at mschaffer@oskyherald.com