As his mom leaned over the cake to blow out the candles, her hair caught on fire. Bieber put out the flames and his mom wasn't hurt.
Bieber later tweeted about the incident saying, "Sick show in Berlin... brought @studiomama on stage 2 sing her happy bday but she lit her hair on fire with the candles. lol. I saved her."
Bieber's mom also tweeted about the fire, thanking her son for the cake and for embarrassing her on stage.