ST. PAUL (AP) - Authorities are warning Minnesotans about the dangers of a new drug called marijuana wax, and they're blaming a manufacturing operation for a November house fire that killed a St. Cloud woman.

Stearns County prosecutors on Wednesday filed third-degree murder charges against two men in the death of 85-year-old Sally Douglas.

Marijuana wax is a street name for marijuana concentrates. It packs a more potent high because THC levels range between 30 and 90 percent in marijuana wax compared with 14 percent in typical marijuana.

Two teenagers recently overdosed on marijuana wax in Duluth.

Clandestine manufacturers use highly flammable butane to extract the THC from marijuana leaves, which the Department of Public Safety says has resulted in a number of fires, explosions, deaths and injuries across the country.