Zac was on set filming for his newest movie, The Greatest Snowman, and as MTV News reports, a staged fire on set turned into an IRL fire, and Hugh had to carry Zac out of the building (which was planned for their scene anyway.)
At the time, neither new how dangerous the situation actually was.
"It started to get late, and some of the pyrotechnics got a little bit too hot," Zac said. "We burst out of the building. It looked great on camera. We didn't know it [at the time], but it was pretty intense. I watched playback, and he saved me from a burning building. It later exploded that night. It was a set, but later it burned down."
But, as expected, Zac later went on to explain that being saved by Hugh was "every girl's dream," and yeah, we totally agree.
Thankfully nobody was hurt in the process.