Since headquarters decided to take over the case, Chris and Jimmy felt somewhat relieved. For cases they had never handled, besides the initial excitement, they were actually very cautious step by step, like walking on thin ice.
Especially now that they had discovered the car they were chasing was rigged with a bomb, a single mistake could be fatal. As Jimmy waited in the parking lot for the bomb squad, he was far from calm. He was genuinely scared during those moments, thinking about the disastrous impact if the bomb had been detonated on the streets while they were chasing the car. Jimmy and Chris might have even been held accountable.