Investigators found an ` ` improvised launch device '' outside of Yokota Air Base , officials say . Residents report hearing two small cannon - like explosions at about 8 am local time . No injuries or signs of violence have been reported , authorities said .
Investigators found an `` improvised launch device '' outside of Yokota Air Base , officials say . Residents report hearing two small cannon-type bangs at about 11 p.m. local time . No injuries or points of impact have been reported , authorities said .