What is the procedure if a fire alarm sounds in the engine compartment of a passenger coach while driving through a tunnel?

1. Stop immediately in the middle of the tunnel lane and lock all doors
2. Accelerate to 150 km/h inside the tunnel
3. If the coach can still leave the tunnel safely, drive out; otherwise stop as far right or in a lay-by, switch on hazards, shut down, evacuate passengers away from smoke via signed exits, and alert the tunnel control center or emergency services
4. Tell passengers to ignore the smoke and stay seated