BUFFALO, Minn.—A man who opened fire at a Minnesota health clinic, killing one staff member and wounding four others, previously threatened to carry out a mass shooting at the facility, according to a police report. Gregory Paul Ulrich, 67, was arrested in Tuesday’s attack at an Allina clinic in Buffalo, a community of about 15,000 people roughly 40 miles northwest of Minneapolis. He remained jailed in Wright County on Wednesday and was expected to appear in court Thursday. County Attorney Brian Lutes said he would charge Ulrich with second-degree intentional murder, four counts of attempted first-degree premeditated murder, and possession of explosive devices. Ulrich has a long history of conflict with medical clinics in the area and had been unhappy with the care he had received, Buffalo Police Chief Pat Budke said. According to a police report, Ulrich threatened to carry out a mass shooting at the clinic in October …