Avoid ignition sources. Immediately extinguish all naked flames. Do not operate electrical switches or devices such as a radio or mobile phone. Do not start the vehicle engine. Do not smoke.
Open all windows and doors.
Evacuate all persons from the vehicle.
If possible, close the gas cylinders from the outside.
Have the entire gas system checked and, if necessary, repaired by qualified personnel.
Only then put the gas system back into operation.