Normandy, MO, police K-9 Argo died Wednesday from injuries he suffered in a fall while on duty.

Normandy Officer Matt Miller and Argo had just finished an accident investigation along Interstate 70 on Sunday when a hail storm moved in. Miller sought shelter inside a parking garage on the University of Missouri-St. Louis campus as officers in his department typically do to avoid damage to their cars, said Sgt. Tim Conner, Normandy canine supervisor.

Miller believes the storm spooked Argo, and he let the dog out of his car to calm him down. Suddenly, the dog ran toward a wall where hail could be heard slamming on the other side. The wall deceivingly looked to be level with the ground but was actually about four stories above ground, Conner said.

Initially, vets told Miller that Argo, a 3-year-old German Shepherd, suffered some broken ribs, a broken leg and a possibly punctured lung. He appeared to be improving, even standing on his back legs with his paws on a table at one point, Conner said. But his internal injuries worsened and he died about 10 minutes after his handler left him Tuesday night, Conner told the St. Louis Post-Dispatch .