The relatives of three men who were killed at a nightclub in Florida this summer are suing Twitter, Google, and Facebook after accusing those social-media companies of providing "material support" to the gunman.
Omar Mateen killed 49 people and wounded 53 at the Pulse nightclub in Orlando in June -- the deadliest mass shooting in modern U.S. history.
Mateen, who was killed by police after the attack, had pledged allegiance to the Islamic State (IS) militant group.
The families of three victims of the attack claim Twitter, Google's YouTube, and Facebook "provided the terrorist group [IS] with accounts they use to spread extremist propaganda, raise funds, and attract new recruits."
The lawsuit alleges the "material support has been instrumental" to IS's rise and has "enabled it to carry out or cause to be carried out, numerous terrorist attacks."
The lawsuit was filed on December 20 in a Detroit federal court.
Facebook said in a statement on December 20 that it is "committed to providing a service where people feel safe when using Facebook."
Facebook, Google, Twitter, and Microsoft said this month they would improve their coordination in removing extremist content and share digital "fingerprints" with each other.
Based on reporting by Reuters