Facebook on Friday said it is tightening live video streaming rules in response to the service being used to broadcast deadly attacks on two mosques in New Zealand. The Christchurch massacre -- carried out by a lone gunman who opened fire on worshipers at two mosques -- claimed 50 lives. Many people have "rightly questioned how online platforms such as Facebook were used to circulate horrific videos of the attack," chief operating officer Sheryl Sandberg said in an online post. "In the wake of the terrorist attack, we are taking three steps: strengthening the rules for using Facebook Live, taking further steps to address hate on our platforms, and supporting the New Zealand community," she added. Facebook is looking into barring people who have previously violated the social networks community standards from livestreaming on its platform, according to Sandberg. The social network is also investing in improving software to quickly identify edited versions of violent video or images to prevent them from be shared or re-posted. "While the original New Zealand attack video was shared Live, we know that this video spread mainly through people re-sharing it and re-editing it to make it harder for our systems to block it," Sandberg said. "People with bad intentions will always try to get around our security measures." Facebook identified more than 900 different videos showing portions of the 17-minutes of carnage.