SALT LAKE CITY (AP) — A Salt Lake City man accused of plotting a mass shooting at a downtown shopping center is set to make his first court appearance.

The 42-year-old Jack Harry Stiles was booked into jail Monday on terrorism threat charges. He's scheduled to be in court for the first time Thursday afternoon. Tipped off by a hospital crisis worker, police learned of Stiles' plans in mid-August.

Prosecutors say he planned to randomly shoot people at the City Creek shopping center on Sept. 25, the anniversary of his mother's death. He also planned to open fire at a movie theater and wire a bomb underneath a transit bus. Court documents show Stiles didn't have any weapons but was planning to buy two guns with silencers and stock up on ammunition. His motive is unclear.