In the days after a gunman killed five people at a gay nightclub in Colorado last month, much of social media lit up with the now familiar expressions of grief, mourning and disbelief.

But on some online message boards and platforms, the tone was celebratory. “I love waking up to great news,” wrote one user on Gab, a platform popular with far-right groups. Other users on the site called for more violence.

The hate isn’t limited to fringe sites.

[...]“I don’t think people understand the state of danger that we’re living in right now,” said Jay Brown, senior vice president at the Human Rights Campaign and a transgender man. “A lot of that is happening online, and online threats are turning into threats of real violence offline.”