The officer was hospitalised and is continuing to receive medical treatement, Nottingham Police added.
So far in the ongoing investigation, two men, aged 24 and 30, and two women, aged 25 and 21, have been arrested on suspicion of assisting an offender.
A man, 35, and a woman, 33, have also been detained on suspicion of possession of a firearm with intent to endanger life and assisting an offender.
The pair remain in police custody.
