HallowZOOeen is officially underway at the Tulsa Zoo.
Families and little kids have been turning out in costumes this week.
It's a spooky, but not too scary, trick-or-treat event.
It draws about 15,000 people during its run each year.
Along with a Pirate Island, you can jump on the haunted train ride.
It's open Halloween night from 6:30 to 8:30 p.m.
It costs $8 to get in and kids under one are free.