The Coast Guard is investigating after a series of red flares were set off near Willard Beach and Casco Bay, signaling false alarms and wasting the agency’s resources.

Bystanders spotted one flare at Fishermen’s Point along South Portland’s Willard Beach early Monday . That came after back-to-back reports of flare sightings near Willard Beach on Dec. 27 and 28, the guard said in a statement Monday.

“Spent flare casings were located on Willard Beach, but no other signs of distress were found,” the guard said.

All told, the three false alarms cost the agency more than $28,000 over the course of three searches that stretched more than 80 miles and included help from a handful of partner agencies, the guard said.

“False reports of distress are serious,” said Capt. Matthew Baker, the Coast Guard’s Northern New England sector commander. “They unnecessarily endanger our crews and needlessly cost the taxpayers money.”

Red and orange flares are international signs of distress, the guard said. Faking such calls can result in criminal and civil penalties, including imprisonment, fines and reimbursement of costs associated with the search.

The false flares follow a series of fake radio distress calls made in October near Mount Desert Island and Great Cranberry Island.

Anyone with information is asked to contact the guard’s investigative service online or at 833-449-2407.