A 15-year-old was arrested in connection with a mass shooting in Seattle on Sunday that killed two people and injured four.

The 15-year-old is just one of two suspects. The two are believed to have opened fire on each other and shot several bystanders in the crossfire. Seattle Mayor Katie Wilson said the teenager was being held in juvenile detention for firearms violations and first-degree assault. Police are searching for a second suspect and still don’t have a description of them.