Pediatric patients at a cancer treatment and research hospital in Houston, Texas, got a super surprise on Thursday morning.

Individuals wearing comic book hero outfits rappelled down the side of the University of Texas MD Anderson Cancer Center building and waved to the kids watching from inside their rooms, according to CBS 11.

The heroes included Superman and Batman, and Iron Man also made an appearance to bring joy to the children fighting cancer.

Video footage showed the superheroes getting ready to descend from the building’s roof, then bravely going over the edge:

In a live video, Superman and Batman performed gravity defying stunts such as flipping upside down and flying past each other as they kept waving to all the people watching them:

At one point, Superman and Batman threw Iron Man a rope and reeled him into their perch on a window ledge. A few moments later, the three leaped from the ledge and continued the impressive show.

“While the superheroes took on window washing duties, just as much cheer was being spread inside the building,” ABC 13 reported.

The patients enjoyed gifts and a visit from Santa Claus, one of his elves, and a reindeer with a sleigh.

MD Anderson’s vision is to be “the premier cancer center in the world, based on the excellence of our people, our research-driven patient care and our science,” according to its website.

Facebook users thanked the superheroes for making the children’s day special and one offered to join the group next time.

“I’d so volunteer to be cat woman or super woman! And bounce off the walls! This is Amazing!” the person wrote.

“Very cool! We need this in a time and season we live in. I’m sure it’s blessing a lot of kids. Thanks to these brave guys!” another user commented.