Hey there, I approved this PK because you initiated fire next to and seemingly at police. The guy wasn't shooting at you on either clip, he was aiming for the other guy in the construction outfit. It appears like you opened fire after seeing him shoot a bullet in front of you at the package carrier, then after directly aimed your weapon at police who were also engaged, getting into a shooting match where you were outgunned.. Regardless of it you were trying to protect the package carrier, you did it directly next to several officers, firing in their direct. The other person, also made that mistake and gave a calculated risk to his main character and was PKed accordingly. If you had not equipped your gun and reacted. You'd have not been PKed.
I will admit this a tricky situation with the event going on and expanding rules. While I may think this valid. It will be reviewed and decided by another staff member.