What actions are needed and what precautions should be taken in the event of a hydrogen fire?

After moving people to a safe location, if it safe to do so, isolate the source of hydrogen feeding the fire. Burns and explosions are hazards when exposed to a hydrogen fire. For more best laboratory preventative safety practices as well as first responder response to a hydrogen incident See both CHS training resources: 

• https://www.aiche.org/ili/academy/courses/ela210/hydrogen-laboratory-safety
• https://www.aiche.org/ili/academy/courses/ela253/introduction-hydrogen-safety-first-responders