Hello lulu14!
    What a crazy moment that must have been for you! Based on your descriptions, it sounded as if the children were waiting for lunch. Moments where children have to wait, (waiting in line, waiting for a turn, waiting for activities to start etc.) are invitations for discipline problems. Therefore, it is important to plan for these transition times. In your case,if the children waiting for their lunch, I would recommend singing songs, or doing fingerplays or play Simon says. Distract them  while they wait.
    However, If the problem started during lunch, I would give a natural consequence for the negative behavior. When the child starts banging, calmly and firmly remind the child that spoons and plates are used for eating food not banging, maybe add in how it makes the food spill and banging makes it hard to hear each other talk etc. If the offense is repeated, tell the child if they do it again then they will have to leave the table and be done with their lunch. If the child continues to do it, then you must stick to your word and carry out the consequence. Stay calm and firm. Do not show the child that their negative behavior is affecting you.