Members of the Muslim community attend the National Remembrance Service at North Hagley Park in Christchurch on March 29, 2019.  The remembrance ceremony is being held in memory of the 50 lives that were lost in the March 15th mosque shootings in Christchurch. / AFP / Sanka VIDANAGAMA
Members of the Muslim community attend the National Remembrance Service at North Hagley Park in Christchurch on March 29, 2019. AFP

Social media companies grapple with how to moderate content in wake of Christchurch attacks