Texas gunman had threatened school shootings on social media, reports say

Teenager displayed worrying behavior in the months before the Uvalde attack, schoolmates tell news outlets

Warning signs were reportedly mounting in the months before the 18-year-old gunman in Uvalde, Texas, opened fire on a classroom of young children and their teachers four days ago in what would become America's deadliest school shooting in a decade.

The teenager had used the social media app Yubo to threaten school shootings and rape, as well as to show off a rifle he had bought, CNN reported on Saturday.