Boardgaming is not a matter of life or death...
...it's much more important than that!
May I ask why? I don't see a thematic or a mechanical problem with firefighter asking a treated victim to follow while she is carrying a gasoline canister outside.
IDKIFAF but I think paramedics are not trained in any real fire fighting techniques. So except grave circumstances, the risk of taking a hazmat and a victim with you would seem to be to high, as the paramedic is not able to assess the risks concerning hazmats properly.
Also AFAIK the prime directive of paramedics is to concentrate solely on victims.
But since it is not covered by the rules you have to forbid it with a house rule/local amendment.