Witnesses to a mass shooting in the US city of Minneapolis have described the terrifying scenes after an attacker opened fire on a church where children were celebrating Mass on Wednesday morning.

One young boy described being protected by a friend who got hit himself. Tragically, two children lost their lives and 17 others were injured in what the FBI is investigating as an anti-Catholic hate crime.

The attacker, identified as 23-year-old Robin Westman, died at the scene from a self-inflicted gunshot wound. Authorities have yet to determine a motive.

Weston Halsne, a 10-year-old survivor, explained his ordeal to CBS affiliate Station WCCO: My friend saved me... he laid on top of me, but he got hit. He expressed relief that his friend was now recovering in the hospital, while also admitting the shock of the situation, stating, We practice it every month, but not in church.

The shooter reportedly fired dozens of shots into the Annunciation Church, which also houses a school, using three firearms. Witnesses described the shock and confusion they felt when the shots rang out, with some initially misinterpreting the sound as construction work.

Locals and officials further recounted the horrifying aftermath, with children emerging from the church covered in blood, one pleading for help with a head wound. A vigil for the victims, attended by hundreds, underscored the community's grief and disbelief.

In response to the tragedy, Minnesota Governor Tim Walz expressed sorrow at the continued occurrence of such violence in the U.S., and condolences were extended at the national level, including from President Donald Trump.

The incident has sparked outrage and calls for action, with survivors and their families grappling with the aftermath of this shocking event.