Have you ever been the last to arrive at a party and the host introduces you, one at a time, to everyone there? So how many of those names are you able to remember? It’s the same way when you introduce characters in a cluster, listing them one after another in your story, your script or your speech. Your readers or audience will have an impossible time keeping all your characters straight for the remainder of the story.
If you simply must introduce more than one character in a scene, give each character her own paragraph (if it’s a written story), her own description, and her own dialogue before moving on to the next new character. And if the hero of your story is introduced as part of a group, introduce her first.