[Theoria]

'Why would they let weapons stay in a trunk of a car all day, is that normal procedure? '

I don't know if they knew that was 'his' car until the end of the day. The most obvious thing would be to secure the area, get first aid. Then begin the investigation. Every room had to be cleared. The process can take some time.

[Las Vegas Ron]

That’t the thing though, discovering what was in the trunk happened first thing that morning. Even Vance talked about it in his mid day presser.

And they always immediately look for cars and search them for potential bombs.