Collapsed concrete walls and twisted wooden beams were among the hazards emergency services and medical teams had to deal with at an intense training exercise.
The drill at Southampton General Hospital simulated the aftermath of an explosion and included about 100 people with casualties being played by volunteers.
Teams attended from Hampshire Fire and Rescue Service, South Central Ambulance Service, Hampshire and Isle of Wight Air Ambulance and University Hospital Southampton NHS Foundation Trust.
Redbridge Hill station commander Paul Riddell said:
“These exercises are invaluable in making sure we are as prepared as possible for any major incident.
“It gives us a chance to practice with other emergency services, gain a greater understanding of the way each other work and develop relationships - all of which could prove to be vital.
“We hope the public will be reassured to know that we practice a large number of scenarios all aimed at protecting the community.”
The exercise on Tuesday was led by the Trust which had been planning it for six months.
It was held in a disused wing of the building and hospital activities were not disrupted.
Els Freshwater, an advanced clinical practitioner at UHS, said:
“As a trauma centre, our clinicians would play a major role in managing critically injured casualties and liaising with our partners in this type of situation, so this activity will enable us to see what we already do well as a group and where we could improve.”