Originally posted by BIT Bear:

have you tried the "killall" command?

https://valheim.fandom.com/wiki/Console_Commands#Cheat_Commands

or maybe look into debugmode and spam press K in the area

Nope that doesn't work. I think cuz seagulls aren't agresive mobs... :(

Upd: i've even tried to create different events (e.g. surlings, dragons) but no result...