French prosecutors have opened a criminal investigation into TikTok for failing to safeguard the mental health of children on its platforms.

It’s the first time the protection of minors on social media has led to criminal proceedings, marking a significant escalation in regulators’ push to protect children on the internet.

The probe comes after a parliamentary inquiry led by Socialist lawmaker Arthur Delaporte, which presented its findings on Sept. 11.

A criminal investigation was opened by the Paris police’s cybercrime unit at the end of October, Delaporte wrote in a press release welcoming the news.

“Our commission’s empirical observation is that of an algorithmic trap that, in just a few interactions, increases exposure to harmful, anxiety-inducing, and depressing content,” he previously said.

TikTok is regulated as a Very Large Online Platform by the European Commission under the EU’s Digital Services Act. The EU has been investigating TikTok for lapses in the protection of child users.

TikTok and the Commission did not immediately respond to POLITICO’s request for comment.