It is either post traumatic stress reaction or mixed anxiety and depression. If it is not decreasing by itself, than needs medication.

Hi, I am sorry for the incidence that had occurred, during that situation, normally most of them will be feeling shock, sadness, stress. But you have to overcome the negativity and proceed positively in future life activities. At present you might be feeling anxious , also you don't have the courage to face the difficult issues and losing the confidence of yourself. don't prolong it, at the earliest visit any psychologist near your place. through counselling (therapies) they can help you to overcome the feelings, if required they can refer for further investigation for medical support. take care stay positive.

Hi. I am sorry to hear about your colleagues. Some feeling of sadness is normal after such events. But when it starts impacting your life and becomes prolonged, as in your case, it becomes necessary to seek help. Depression is a treatable condition and you can overcome your current symptoms with adequate treatment with medications and psychotherapy.