There was no immediate information on any injuries but Governor Tim Walz called the Wednesday morning (late night AEST) shooting “horrific”.
The Minneapolis city government said the shooter had been “contained” after the gunfire at the Annunciation Church’s school, and there was no “active threat” to residents.
US President Donald Trump said in a Truth Social post that he was briefed on the “tragic shooting” and that the White House would continue to monitor the situation.
The pre-kindergarten through eighth grade school had an all-school Mass scheduled at 8.15am (11.15pm AEST), according to its website.
Monday was the first day of school, and social media photos from that day show students in green uniforms greeting each other at bicycle racks, smiling for the camera and sitting together.
At a meeting of Democratic officials elsewhere in Minneapolis, Democratic National Committee Chair Ken Martin noted the shooting and “unknown amount of victims”.
The gunfire was the latest in a series of fatal shootings in the city in less than 24 hours.
One person was killed and six others were hurt in a shooting on Tuesday outside a high school in Minneapolis. Hours later, two people died in two other shootings in the city.
Wednesday’s school shooting also followed a spate of hoax calls about purported shootings on at least a dozen US college campuses.
The bogus warnings, sometimes featuring gunshot sounds in the background, prompted universities to issue texts to “run, hide, fight” and frightened students around the nation as the school year began.
