Two children have been killed and 17 people injured after a shooting at a Catholic school in Minneapolis.

The attack happened after 08:00 local time (14:00 BST) at Annunciation Church, where children had been attending a worship service during their first week of school.

The FBI is investigating the incident as an “act of domestic terrorism and hate crime targeting Catholics.”

Here’s what we know about what happened.

The attacker has been identified as 23-year-old Robin Westman, from suburban Minneapolis.

Westman’s motive is currently unknown.

The attacker was described as being dressed in all black and carrying three weapons – a rifle, a shotgun and a pistol. A smoke bomb was also found in a vehicle police believe belonged to the suspect in the church car park.

Minneapolis Police Chief Brian O’Hara said the attacker did not have an “extensive known criminal history”, and acted alone.

The motive remains unknown, O’Hara said, adding that police cannot currently confirm a relationship between the suspect’s family and the school.

Police did find a “manifesto” the suspect timed to publish on YouTube at the time of the shooting. The FBI assisted officials and took it down.

“Our hearts are broken for the families who have lost their children”, O’Hara said, as well as for the young lives “fighting to recover” and for “the entire community that has been so deeply traumatised by this senseless attack”.

Two children, aged eight and 10, were killed. Seventeen people were also injured, 14 of whom are children.

The attacker is also dead, police said.

The three adults who were injured are all parishioners in their 80’s, O’Hara said.

Thomas Wyatt, chairman of emergency medicine at Hennepin County Medical Center, said seven children aged between six and 14 years old were brought to his department and were in critical condition, with four needing surgery.

Non-critical patients were taken to other hospitals.

All injured victims are expected to survive, officials said.

“These were Minneapolis families,” Mayor Jacob Frey said during a briefing. “These were American families, and the amount of pain they are suffering right now is extraordinary.”

Making a pointed reference to what some perceive as political responses to mass shootings, Frey – a Democrat – said: “Don’t just say this is about ‘thoughts and prayers’ right now. These kids were literally praying.”

Annunciation Catholic Church and its faith-based school is for students from preschool (nursery-level) up to Grade 8 (aged 14 years old), according to its website.

The Catholic school’s approach to teaching is one of faith-based learning.

The school added that religion “compels” it to engage with its local community. It also has a sister school in Haiti.

Principal Matt DeBoer spoke at a press conference on Wednesday and began his remarks by saying “I love you, I’m so sorry this happened today”.

He thanked well-wishers for their thoughts and prayers and asked people to “pray with our feet” to take action against future shootings.