What immediate action must a driver take if the low air pressure warning buzzer and red warning light illuminate (pressure falling below ~5.5 bar) while driving?

1. Increase speed to spin the engine faster and force the compressor to build pressure quickly
2. Ignore the alarm until the next scheduled delivery stop
3. Switch off the vehicle's electrical master switch while coasting
4. Safely bring the vehicle to an immediate controlled stop off the active roadway before the spring emergency brakes lock up automatically