An optical illusion tricked firefighters into thinking a building was burning

On Halloween night, firefighters in Ireland were tricked by an optical illusion when a building appeared to be burning. 

The Dublin Fire Brigade posted a video of the illusion on Twitter, and it's seriously confusing the internet. 

Take a look at the puzzling video. 

While it looks like there is a fire in the second-story window, the fire department explained that the building was not, in fact, burning. It was actually just the reflection of a "large bonfire in the city centre."

If you look closely, the fire is only a reflection — it's not inside the building.

Take a second look at the illusion and you'll see the reflection on the third floor as well. 

The department said that they responded to 337 fire calls on Halloween night — about 200 of which were Halloween related, like uncontrolled bonfires. 

Visit INSIDER's homepage for more.