we believe acquired a gun somehow, don't know how, and picked up the gun and returned fire in the direction of the shooter that we have in custody. >> reporter: this incident comes just one day after two other mass shootings. in baltimore, where a community block party descended into chaos as gunfire erupted, killing two and injuring two others, and in wichita, kansas, nine people shot and wounded at a nightclub. in philadelphia, the mayor saying he's horrified by the shooting, writing my heart is with the loved ones and families of everyone involved. i sent my prayers to the victims. this crime scene is pretty expansive. authorities will be back out there this morning canvassing for more clues. at this point, police have not released the names of the two suspects they apprehended. no word on a motive as the investigation is just beginning. >> never seems to end. hopefully those two children