Both got into a car and fled leaving their guns behind.
Now, why would you want to get into a car with a robber that you just shot? And why would you leave your gun behind?
Can no one write a coherent story anymore?
Because it’s too difficult to write “Both suspects got into...” when you can simply write “Both got into....”? I agree with you that this is simply poor writing.
Brevity at the expense of clarity—a very common behavior among our professional “writers” now.