First identified as a cow, the bull was cornered while running around the soccer fields on the south side of Prospect Park.
It then continued to roam through the field, as a large crowd gathered outside a fence.
VIDEO: Watch highlights of the bull's run here:
Animal officials eventually tranquilized the bull took it away from the park, after several hours of trying to corral it.
There's no word yet how the bull got loose, or what will happen to it now.
Multiple people spotted the bull as it started its journey through the area:
There's a cow roaming the streets of Prospect Park.— Aaron Porchia (@Porchia) October 17, 2017
Cow on the moove in Brooklyn— Katie McDonough (@kmcdonovgh) October 17, 2017
Just saw a COW bolting up 17th St in S. Slope. On the sidewalk. In case I thought there was nothing new to be seen after a lifetime in NYC.— RosieSchaapofHorrors (@rosieschaap) October 17, 2017
FDNY officials said a child who was in a stroller was injured when the bull apparently knocked the stroller over. It happened near Park Circle and Prospect Park Southwest.
The child was taken to a nearby hospital for treatment. It's not clear how seriously the child was hurt.