FRANKFORT, Ky. — Public health officials say at least 12 drug overdose deaths occurred in Kentucky during the Labor Day weekend amid reports of more potent shipments of heroin circulating in the state.

The Kentucky Department for Public Health says preliminary reports show 15 overdoses — 12 of them fatal — during the three-day holiday weekend were reported to the agency.

Health officials say the preliminary number is based on reports from hospitals and emergency medical personnel, but it doesn’t represent a final total.

Officials don’t yet know how many overdose deaths were linked to heroin use.

The holiday death toll comes amid reports of increased overdoses linked to heroin mixed with fentanyl and other dangerous substances. Department for Public Health Commissioner Dr. Hiram Polk calls drug overdoses a public health crisis.