Here are some tips:
Imagine it in slow motion so you feel pressured to write fast to 'keep up' with the action.Even though it it fast paced action, it shouldn't be rushed through.
When describing, think about the emotions of the character/s as well as what they might be thinking at that moment, feeling, what they are seeing, hearing and tasting.
Read books with action, one wattpad and off the shelf. This way you can begin to recognise what triggers the action, how to introduce it and get more ideas of how to write it.
It will familiarise you with how to write action effectively.
When your ready to start writing the scene, make sure tension has been built in the story narrative to provide maximum effect.
Spend time over developing the scene. You don't have to write it straight away. You can spend time thinking and planning it.
Do you normally avoid action or fighting scenes?