Rule 285 ↗
If an incident involves a vehicle containing dangerous goods, follow the advice in Rule 283 ↗ and, in particular
switch off engines and DO NOT SMOKE
keep well away from the vehicle and do not be tempted to try to rescue casualties as you yourself could become one
call the emergency services and give as much information as possible about the labels and markings on the vehicle. DO NOT use a mobile phone close to a vehicle carrying flammable loads.