Supermarket Shooting - Ridiculous plot

So the clerk didn’t notice a gun right in front of his face? And if no, why did he become so scared and passive?

None of the other customers saw the gun? So they just got on the floor because the guy told them to get on the floor?

There was no video surveillance footage in a large NYC supermarket?

After the shooting, when the police (especially Jaime Lee) noticed the gun was missing, you’re telling me they didn’t question / search all the people in the supermarket for the gun? They just let all the possible witnesses go home after the shooting?

And even still - If you ignore the above and go with the movie’s plot that nobody saw the gun - that doesn’t mean there wasn’t a gun. The clerk, for example, just said he wasn’t sure; his statement doesn’t rule out that there wasn’t a gun. So without evidence of the contrary, why wouldn’t the police chief take Jaime Lee Curtis’s word? If she said it was a gun and nothing rules out that it wasn’t a gun, then give her the benefit of the doubt. How do you suspend for excessive force without proof that there was no gun?