A major incident “live-action” exercise is under way at a railway station in Surrey.
A large emergency service presence is visible near Guildford station, with about 300 responders attending to 100 incidents.
South East Coast Ambulance Service (Secamb) said the public should “be aware and not alarmed” by the drill, which is due to end at 14:30 BST on Thursday.
Sgt Olly Brown said the exercise allowed each service “to understand each other more effectively, which ultimately saves lives”.
The exercise is being conducted by partners in the Surrey Local Resilience Forum, which works to ensure the county is well prepared for emergencies.
As well as Secamb, these include Surrey Police, British Transport Police, Surrey Fire and Rescue, Network Rail, Surrey County Council, Royal Surrey County Hospital and Guildford Borough Council.
The Environment Agency, Rail Accident Investigation Branch, South Western Railway, Great Western Railway, Avanti West Coast, the Rail Delivery Group and Surrey 4×4 volunteers are also involved.
Secamb emergency preparedness, response and resilience manager Dave Nelson said: “This pre-planned exercise is an important part of us being assured of our resilience and response plans which we will review and strengthen where required after the exercise.”