Two of the nine people wounded in a weekend shooting at a suburban Detroit splash pad remain hospitalized in critical condition, including an 8-year-old boy who has shown significant improvement despite being shot in the head.

His 4-year-old brother and their mother were also injured in the attack in Rochester Hills. The shooter, Michael Nash, 42, fired up to 36 times before returning to his home and killing himself.

Authorities are still investigating the motive, noting Nash had no connection to the victims or the splash pad.

Interviews with Nash’s mother revealed he exhibited signs of paranoia and possible mental health issues.

Michigan’s new law allows judges to remove firearms from individuals deemed a threat by family members, the Associated Press reported.

The 9 mm Glock used in the shooting was legally purchased by Nash in 2015, and investigators found 11 more weapons at his home.

The incident was one of several mass shootings in the U.S. over the weekend, including incidents in Lathrup Village, Michigan; Methuen, Massachusetts; and Round Rock, Texas.

Written by B.C. Begley