Hydrogen in gas form is non-toxic. It is non fragrant, color and tasteless. Unlike, for example, LPG, it is much lighter than ordinary air, so that it rises quickly. The auto-ignition temperature is much higher than, for example, for LPG, petrol or diesel. The risks in a vehicle fire with the last mentioned fuels are therefore higher than with hydrogen.
The pictures below show the effects of a fire in a hydrogen car and a fire in a car on gasoline.
Source: http://www.evworld.com/article.cfm?storyid=482
Worldwide, many millions of kilometers have been driven with hydrogen vehicles and a proportional number of refueling has taken place. All without incident.
For example, Mercedes has driven a total of 18 million kilometers in cars with fuel cell systems.
Three Mercedes B-class F-Cells drove a trip around the world without any problems (with the exception of a minor collision with a Lada in central Russia – but that was not due to the hydrogen!).