Authorities' awareness of one of the gunman's past behavior raises questions about whether the attack could have been thwarted.

A 75-page manifesto believed to have been penned by Vazquez and Clark described Mymy as “based racist nationalist” which “accounts for the Nazis and Chuds who love the show.”

A man was arrested outside the Lakeville Mosque on Friday after claiming to be a military officer and federal agent after causing a "disturbance" before police were called.

A male is in custody after a disturbance at a mosque in Lakeville, Minnesota, on Friday, according to police. Officials said officers found two knives in his pockets while arresting him, though they have "not received any information to suggest" he targeted the mosque for religious purposes.

San Diego police swarmed the home tied to accused mosque shooter Caleb Vazquez on Friday, transforming the residential property into a sprawling crime scene as detectives hauled out boxes and evidence bags.

Details about the lives of the shooters suspected of killing three men at the Islamic Center of San Diego are beginning to emerge.