Why wouldn’t the witness describe the sound of a car crashing into something?
From the article: “Aanchal Jaiswal, who lives nearby, described hearing something banging into something else followed by two shots.”
They just weren’t directly quoted on it.
On your other two things: Of course be skeptical, but also be skeptical of whatever the person writing the article got wrong, e. g. the car may have started “moving” and pinned the officer but the journalist used the word “leaving”. And police often don’t release information for an active investigation even when police aren’t involved, so it’s a bit silly to start reading anything into that.
There is a witness (female in the car) so it will be interesting to find out what they say.