Motive unknown in Rochester Hills splash pad shooting

Two of the nine victims shot Saturday at a Rochester Hills splash pad were released from the hospital, the Oakland County Sheriff's Office announced Monday .

The big picture: Investigators have been searching for clues to understand the shooter's motive, per the AP .

• The suspected shooter thought the government was tracking him, and at least 11 guns were found in his home, the Free Press reports .

Catch up quick: The gunman — identified as 42-year-old Michael William Nash of Shelby Township — arrived at the Brooklands Plaza Splash Pad around 5pm Saturday and fired 36 times, injuring nine, the Free Press reports .

• Nash took his own life after the shooting.

What they're saying: "It's our understanding that he was undergoing some mental health challenges, but no one that we know of was notified," Oakland County Sheriff Mike Bouchard said over the weekend.

The latest: A 37-year-old woman and a 77-year-old man who were shot have been released from the hospital, the Detroit News reports .

• The seven other victims remain hospitalized.
• An 8-year-old boy who was shot in the head and a 39-year-old woman shot in the abdomen were in critical condition Monday. A 4-year-old shot in the thigh was in stable condition.

Zoom in: The sheriff's office has verified two GoFundMe pages for victims and warned against scam fundraising efforts.