The owner of a suburban Minneapolis gun shop told The Associated Press that the man who killed two schoolchildren and injured 21 others at a Catholic church last week showed no signs of troubling behavior during a visit to the store days before the attack.

Kory Krause, owner of Frontiersman Sports in St. Louis Park, said Robin Westman spent roughly 40 minutes in the shop on Aug. 23, examining several firearms and ultimately buying a revolver. Krause said staff saw nothing in their interactions to suggest imminent violence and that Westman completed the required background checks and held a valid permit to purchase the handgun.

Investigators say Westman carried out the Aug. 27 attack at the Church of the Annunciation in Minneapolis while students from the affiliated Annunciation Catholic School were gathered for their first Mass of the academic year. Authorities recovered a semiautomatic assault-style rifle, a shotgun and a handgun at the scene. Officials have said Westman was legally entitled to buy those weapons, and Krause said the firearms recovered in the attack did not come from Frontiersman Sports.

Surveillance video from the store showed Westman examining multiple guns before purchasing the revolver, Krause said. The revolver he bought was not among the weapons later found at the church, according to the owner and investigators.

Law enforcement agencies continue to investigate the source of the assault-style rifle and other firearms used in the shooting and are working to piece together a timeline of Westman’s purchases and movements in the days leading up to the attack. Officials have not disclosed all details about where the recovered weapons were acquired.

The killings and injuries at the church have drawn renewed national attention to gun policy, background check procedures and the regulation of certain types of firearms. Kansas-based Frontiersman Sports’ account of the sale underscores that federal and state checks cleared the purchaser for the handgun he acquired at the store.

Krause said his staff members were shaken by the violence and are cooperating with investigators. Authorities have said the investigation remains active as they seek to determine how Westman obtained the weapons used in the attack and whether any red flags were missed by officials or others who encountered him prior to the shooting.