The attack happened Tuesday morning at an Allina clinic in Buffalo, a community of about 15,000 people roughly 40 miles (64 kilometers) northwest of Minneapolis.
Authorities said Gregory Paul Ulrich, of Buffalo, opened fire at the facility and was arrested before noon.
AdAs 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.
Hennepin County Medical Center spokeswoman Christine Hill said Tuesday night that a person brought to the hospital after being shot at the Buffalo clinic had died.