Series 1 contains fairly mild slapstick violence, at times of higher tension the show still retains its comedic effect, series 2 is largely the same, however a couple of scenes towards the end of the series are quite strong, series 3 is quite a bit darker with its theme of gang related crime, some strong bloody violence and a quite bleak finale.
There is very bloody violence in Season 3 but 1 & 2 have mild scenes of violence
A man accidentally shoots himself in the head, his head is blown off and then explodes leaving blood and skin on the ground
Someone is punched in the face, blood splatters on the window. This is paired with violent scenes (fist fight)