UPDATE: Seward police Lt. Butch Tiner tells Seward City News that the bear was killed not after it swallowed the shell but when the shell pierced the bear's torso and exploded. From the SCN: "It entered the bear behind its ribcage and went through its diaphragm, clipping its lung in the process before exploding and killing the bear. The bear ran back toward Fifth Avenue but died on the sidewalk."
From the Seward Phoenix Log: A Seward police officer trying to chase a black bear out of downtown Seward fired a noisemaker shell at the animal, but the shell didn't explode until after the bear swallowed it.
The officer twice stepped out of his SPD cruiser. ... He fired noisemaker shells to encourage the critter to vacate the scene and move along. However, on the second occasion a freak accident resulted in the death of the bear as it reportedly swallowed the shell, whereupon the shell exploded. ... SPD says that it is looking into developing procedures to better deal with bears wandering into “urban” Seward.
Read more: Two local bears die under fire