HASTINGS, Minn. (AP) — Investigators say a man has been charged in the deaths of a mother and daughter who were killed when a boulder fell from the man's truck and smashed into their car in suburban St. Paul.

Thirty-three-year-old Joseph Czeck was charged Friday with four felony counts of criminal vehicular homicide. Investigators say an 800-pound boulder fell from the truck he was driving Monday in Rosemount, Minnesota.

Czech appeared in court Friday. An unconditional bail was set at $70,000.

Sixty-seven-year-old Karen Christiansen and her 32-year-old daughter, Jena Christiansen, died at the scene.

Czeck, of Hastings, was arrested after police found his landscaping truck Wednesday night. Rosemount Police Chief Mitchell Scott says it isn't clear whether Czeck was aware that the boulder had fallen.

Defense attorney Tayler Rahm declined comment.