Shots fired on Capitol Hill
A quick look-over, and in a situation like this first reports are usually dead wrong. Sounds like all shots were fired by police. There is a video of the woman's car, stopped with front toward the metal posts used on Capitol Hill. Front end shows no damage, doesn't look like it rammed anything. Then she drives out of sight, shots fired, and she drives away (I won't say speeds, in Washington traffic it's hard to drive, let alone speed). Park Police car badly busted up, but looks more like collision with some other vehicle or a still object.
Still photo of car after it stopped shows again, no front end damage at all, but apparent damage to rear end, possibly rammed during chase to try to spin it out. New car, looks like Conn. plates. Small kid in car... starting to sound like possibly a panicked tourist?