If a severe diesel fuel leak is detected beneath the passenger coach during transit, what is the correct emergency handling protocol?

1. Stop immediately in an open safe area away from heat sources and populated areas, shut down the engine, turn off the master electrical switch, evacuate passengers upwind, strictly prohibit smoking or open flames, and notify emergency services
2. Light a lighter to inspect where the fuel tank is leaking
3. Continue driving at high speed to empty the fuel tank quickly
4. Instruct passengers to catch the leaking fuel in paper cups