A 67-year-old man said to be unhappy with his healthcare is accused of killing one person and injuring four others at a US medical centre.
Bomb technicians were investigating a suspicious device left at the scene, as well as others at a motel where Ulrich was staying, authorities said.
All five victims were rushed to the hospital before a hospital spokeswoman later confirmed the death.
Three of the victims remained in stable but critical condition and a fourth had been discharged.
Police Chief Pat Budke said Ulrich has had a long history of conflict with health care clinics in the area.
"All I can say is, it's a history that spans several years and there's certainly a history of him being unhappy with health care ... with the health care that he'd received," Mr Budke said.
Police said it was too early to tell if the shooter had targetted a specific doctor. Court records show the suspect at one point had been ordered to have no contact with a man whose name matches that of a doctor at the clinic.
As authorities searched the clinic for more victims, they found the suspicious device and evacuated the building, Wright County Sheriff Sean Deringer said.
It was not immediately clear whether that device exploded, but TV footage showed several shattered plate-glass windows at the clinic.
