HALF MOON BAY, Calif.—The California Department of Fish and Game says a pair of mountain lion cubs shot by wardens in the backyard of a Half Moon Bay home were about four months old and could not have survived in the wild.

Wildlife advocates previously had criticized state wardens' decision to kill the cubs, asking why officials didn't attempt to tranquilize them before they were shot to death on Dec. 1.

Agency officials originally said that wardens killed two 30-pound cougars because of concerns they might escape and threaten public safety.

But agency director Charlton Bonham said Friday he regrets the "unfortunate incident," after realizing the female cubs weighed 13 and 14-pounds, smaller than previously assumed.

Monterey-based Wildlife Rescue founder Rebecca Dmytryk says wildlife experts should have been notified to assess the danger.