The mothers of two teens, ages 15 and 19, want kids to stop “surfing” BART trains after their sons died after apparently falling from the top of train carriages.

Two teenagers died after falling from trains in San Francisco in the past two weeks. Now, their grieving mothers are sounding the alarm about a dangerous trend of young people climbing onto the top of BART trains and “surfing” them, and posting stunt videos on social media.