Many people in Christchurch and across New Zealand (and even the world) will experience distress such as acute stress reactions and horror following the fatalities in Christchurch - this is a normal reaction to an abnormal situation.
Most people will manage, and the distress will subside over time.
Psychological distress is a normal response to this situation. Distress is not only experienced by people directly impacted, it is also experienced by people witnessing injuries and distress to others.
However, there are will be some people that will have more profound reactions, particularly later on some time after the event, and will require assistance.
Sharing video footage or images on social media and irresponsible media reporting can be extremely unhelpful for vulnerable people, not just in New Zealand, but all around the world. It may trigger previous trauma for them, or if they are directly impacted and have had loved ones harmed or killed, may experience a more intense trauma response. Merely viewing this material and discussing it with people who are vulnerable can also be unhelpful.