On 15 March 2019, 51 people were fatally shot and 49 injured in two mosques in Christchurch. In a statement broadcast on television, Ardern offered condolences and stated that the shootings had been carried out by suspects with "extremist views" that have no place in New Zealand, or anywhere else in the world. She also described it as a well-planned terrorist attack.
In March 2019, the perpetrator of the Christchurch mosque shootings in New Zealand used Facebook to stream live footage of the attack as it unfolded. Facebook took 29 minutes to detect the livestreamed video, which was eight minutes longer than it took police to arrest the gunman. About 1.3M copies of the video were blocked from Facebook but 300,000 copies were published and shared.