action/hook when new order is saved

Hello together.

I write a plugin for woocommerce which has to do something when a new order is placed. I tried to get this information with action save_post but it is not working. It seems save_post and publish_post works only if a post is saved in the backend.

Do somebody knows if there is a action/hook to do something when a customer place a new order on the frontend?!

Thanks in advanced!

https://wordpress.org/plugins/woocommerce/