My 3 year old is being horrible today! She hit her sister in the head with a toy truck. Kicked her…

My 3 year old is being horrible today! She hit her sister in the head with a toy truck. Kicked her off the couch and her sister landed on her head. She keeps kicking her. I don't get it. They normally play and get rough sometimes but this is insane!! Ugh I don't know what to do. Spanking and timeouts don't seem to be working...