The parents of the two schoolchildren fatally shot in a Minneapolis church spoke out for the first time on Friday, with some imploring the shaken community to address the root causes of shootings that target schools.

Fletcher Merkel, 8, and Harper Moyski, 10, were killed on Wednesday morning (local time) when a shooter opened fire at a Mass that hundreds of students at Annunciation Catholic School attended.

Fifteen other Annunciation students between the ages of 6 and 15 years old were shot. Three adults — all in their 80s — were also shot. They have not been identified. Most of the victims are expected to survive, authorities said.

A call to action

In a statement released Thursday, Moyski’s parents described Harper as “a bright, joyful, and deeply loved 10-year-old” who was “adored” by her younger sister.

“As a family, we are shattered, and words cannot capture the depth of our pain,” the statement read.

Parents await news of their children's status after a shooting at Annunciation Church on Wednesday

The 10-year-old’s parents said that they were focused on healing in the wake of the shooting, but added that they hoped Harper’s memory would fuel action that might prevent shootings going forward.

“No family should ever have to endure this kind of pain,” Harper’s parents wrote. “We urge our leaders and communities to take meaningful steps to address gun violence and the mental health crisis in this country.”

Remembered by his life, not death

Fletcher Merkel’s father, Jesse Merkel, tearfully read a statement outside the church where his son was killed, saying the eight-year-old loved his family and friends and enjoyed fishing, cooking and playing any sport.

Because of the shooter’s actions, Merkel said, “we will never be allowed to hold him, talk to him, play with him and watch him grow into the wonderful young man he was on the path to becoming”.

People gather at a vigil at Lynnhurst Park after a shooting at the Annunciation Catholic School, Wednesday

“Please remember Fletcher for the person he was and not the act that ended his life,” Merkel said.

Even as Merkel mourned the loss of his son, he said he was thankful for the “swift and heroic actions” of adults and students inside the church without whom “this could have been a tragedy of many magnitudes more”.

Acts of heroism

Minneapolis doctors and law enforcement echoed Merkel’s sentiment, describing the gruelling escape children and teachers endured, as well as the heroic rescue efforts that saved countless lives.

When one of the students who was injured during the shooting went in for a CT scan on Thursday, she was visibly distressed.

Without hesitation, a nurse at the hospital who was not assigned to respond to the mass casualty event sat with the young girl throughout the procedure — even though safety protocols stipulate that medical staff should clear the room to prevent radiation exposure.

Susan Saly, right, and Meagan Pierlouissi place flowers at a memorial at Annunciation Catholic Church after Wednesday's school shooting

The nurse “put a little lead on, stayed there and held her hand and held her hair while she went through scanners so she didn’t have to go through alone,” Dr Jon Gayken, one of the head trauma surgeons at Hennepin County Medical Center, said.

Several medical first responders — many of whom were stationed just blocks away from the church — have children enrolled at the Catholic school, officials announced.

“Those are the types of things we witnessed yesterday,” Gayken said.

Despite the unimaginable tragedy of the day, Gayken said, there were far less casualties than there could have been.

Children follow active shooter training

Law enforcement officers gather outside the Annunciation Church's school in response to a reported mass shooting

Marty Scheerer, the chief of Hennepin County Emergency Medical Services, credited “unrecognised heroes”, like the children and teachers in the church who followed their active shooter safety trainings, despite the chaotic and incessant hail of gunfire.

Children “protecting other children” often “laid on the floor and covered each other up” while teachers ushered kids to safety.

“That was key,” Scheerer said.

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The first police officer entered the church “without hesitation” just minutes after the 911 call reported the shooting, Minneapolis Police Chief Brian O’Hara said.

Parishioners told O’Hara that it was “the first time that the children and others there had any sense that they might be safe and survive.”

When officers entered the church, they encountered children “that had blood on them from not because they were injured, but because of blood pressure from other kids”, O’Hara said at a separate news conference later in the day.

“There’s going to be countless lessons of bravery, from young children all the way up to elders,” O’Hara said.