Need help how can I kill a rat stuck in a trap?

I was playing around with rat traps trying to catch a squirrel. Instead, it caught a pretty fat rat that is still alive. Im scared it might bite me how can i kill it without it biting me? Or do i just let it suffer until it dies?

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+1 y
I sprayed some wd-40, rodent replellant, bug spray and he is still alive. I really don't want to be messy and kill it with a hammer.
Need help how can I kill a rat stuck in a trap?
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