Relax, they were secured with ropes. Rope swings, actually. In October, 245 people attempted to break a Guinness World Record by going on a simultaneous tandem swing off a 98-foot bridge in Hortolandia, Brazil.
Guinness has yet to certify whether these folks broke the previous record (which was also set by Brazilians), but a good time was had by all. You can see the jump from the vantage point of the bridge and also from a swinger's GoPro at Atlas Obscura.