Encrypted messaging app Telegram announced today that it has shut down access to several public channels that people have used to communicate about ISIS. The news comes after days after the terrorist group waged attacks in Paris that killed more than 100 people. Since then, reports have surfaced about how terrorists have used encrypted messaging in their operations.

“We were disturbed to learn that Telegram’s public channels were being used by ISIS to spread their propaganda,” Telegram wrote today in a publicly visible post in the Telegram app. “We are carefully reviewing all reports sent to us at abuse@telegram.org and are taking appropriate action to block such channels. As a result, this week alone we blocked 78 ISIS-related channels across 12 languages.”

This week the company will be rolling out an easier way to report on “objectionable” content that’s visible to any user, according to the post. For now users can alert Telegram to questionable material by sending an email to abuse@telegram.org. That’s exactly how Telegram figured out what to ban.

In addition to Telegram, people can send encrypted messages with apps like Open Whisper Systems’ Signal.

But Telegram is growing quickly. As of September it was delivering more than 12 billion messages each day.

Update at 1 p.m. Pacific on November 19: Telegram announced that it has shut down another 164 public channels “used to spread terrorist propaganda” today alone.