Training on Managing Major Incidents

I have been requested to locate Training on Managing Major Incidents (For example: active shooters, mass casualty incidents (example vehicle crash with children and adults involved resulting in deaths or serious bodily injuries), large scale incidents that utilizes outside jurisdictions to assist, etc. What we are looking for is not training on the initial response to a major incidences. What we are looking for is training on managing the incident once situation is under control. We are wanting our sergeants and lieutenants to get additional training regarding managing the scene middle, and end.
Does anyone know what schools or programs that I can look into to find this type of advanced training?