CHARLOTTE, N.C. (AP) — Nearly 400 gallons of sewage have been spilled into a North Carolina lake, leading officials to suspend swimming for the weekend.

Rusty Rozzelle, water quality program manager for Charlotte-Mecklenburg Storm Water Services, told local media outlets that the sewage was spilled into a cove on Lake Norman on Thursday.

Rozzelle said Friday that underground boring activities accidentally broke a sewer line, causing the spill. He said a Piedmont Natural Gas subcontractor from Michigan was installing a gas line to a house when it broke the sewer line.

Storm Water Services staff collected water samples, but Rozzelle said the results won't be available until Monday, adding that sampling will continue until bacteria levels are within safe levels.