Halunke24680

[17.11.2018 14:37:37.898] s_m_y_cop_01_black_mini_02 [17.11.2018 14:37:37.898] s_m_y_cop_01_black_full_02  
 
Those peds probably don't exist. Your backup.xml might have a unit you don't have ingame. Probably from a plugin like RDE I think. 
backup.xml Put this in Grand Theft Auto V\lspdfr To solve your issue.
 

Alot of people including me seem to not know how to make the firetruck use the firetruck siren, but thanks to @Iggy Fresh i've found out how to do it!
 
First of all go into OpenIV and go to (mods)/x64/audio/sfx/resident and right click the vehicle.awc and export to openformats. When you've done this open up Modern siren pack for example and find a firetruck siren like the EQ2B siren.  Rename the firetruck wail to ''AMBULANCE_WARNING'' and drag and drop it into the ''vehicles'' folder you got by exporting the vehicles.awc and overwrite the current ''AMBULANCE_WARNING'' Then import the vehicles.oac into OpenIV again.  
Last step is to edit the ELS VCF files.
Start of with opening the .XML file and set the ''SrnTone1, 2 and 3'' to false keeping only ''SrnTone 4'' as the only option, which is ''AMBULANCE_WARNING''.  Then for the other .XML's set all ''SrnTone's'' to ''true'' leaving only ''AMBULANCE_WARNING'' to ''false''.  
So when you're done the .XML should looks something like this
Hope this helped, becuse it helped me! And please move this if i posted it in the wrong section. And again thanks @Iggy Fresh for letting me know about this!