When you have been exposed to a shocking incident you can experience various reactions that protect you psychologically.
Feeling of unreality
You may find it is as if things are stuck or repeat again and again in your memory. Many people experience it as though they are in a movie that is running in "slow motion".
Your senses are heightened, making it possible to assess the situation and act in order to evade dangers.
The way you experience your surroundings in the first hours after the incident is also often different than usual.
Everything can seem unreal and irrelevant, and you can get the feeling of being in a "bubble" or in a nightmare you hope to wake up from soon.
Your body responds as well. It is common to have a powerful and rapid heartbeat and a feeling of nausea. You might feel faint and alternately hot and cold with a tendency to get chills and trembling.