Three people were shot to death and one was critically wounded Tuesday at a known drug house in suburban Salt Lake City, causing temporary lockdowns at several area schools as police looked for two men who may have been involved.

Investigators said a person inside the house reported the shooting in Midvale at about 8 a.m.

Unified Police Department Lt. Justin Hoyal said a search warrant had been served at the residence in recent weeks for drug activity. "It was a known narcotics house," he said.