PSNI Chief Superintendent Stephen Cargin said he believes Pc Philippa Reynolds would have died instantly due to the force of the crash.
Ms Reynolds is believed to have been sitting in the rear driver's side seat when the unmarked police car was hit side on.
More top news
A wanted man asked police to use a "better photo" instead of the "horrible mugshot" they used in a Facebook appeal.
Speaking to ITV News' Mark Austin on the anniversary of the London bombings, ex-PM says nations around the world will need to respond.