The wallaby—an animal resembling a small kangaroo—belonged to a private owner in the city of Houten, Netherlands, 50 kilometers southeast of Amsterdam.
The national police force said that after attempting to sedate the animal, it hopped toward the highway.
The force said that "for the safety of the animal and of traffic, the animal was terminated."
Police spokesman Dennis Janus said that before being shot, the wallaby was hit with three tranquilizer darts, probably containing a lethal dose of sedatives. Officers believed the animal would die painfully if hit by a car.