A 15-year-old boy has been arrested for possessing a device made of drain cleaner that exploded in an Arizona school yard Monday, injuring him and seven others.

Pinal County Sheriff's spokeswoman Lt. Tamatha Villar says the boy told investigators he has been building such devices with different chemicals and reactive agents to see what happened.

Villar says three other boys and four girls at the Queen Creek school suffered minor to moderate injuries, including burns to their hands, arms and faces. One of the girls also appeared to suffer burns to her eyes.

Authorities planned to serve a search warrant at his home seeking a second device.

Queen Creek is about 30 miles southeast of Phoenix.