This, technically, varies by nation.
As a rough rule if the police force are armed with lethal weapons then yes, the state fundamentally reserves the right to kill citizens.
Where the police force are not routinely armed with lethal weapons, is a statement that the state are civilians too. (In practice this is rarely the case due to factors wider than policing.)
Wherever agents of the state assert the right to do things to you that you are not allowed to do to them, they are not civilians.
Wherever agents of the state assert no more rights than civilians have, there is no state.
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