Is it permissible to interrupt prayer to save a child who is choking?

Performing this action is neither forbidden nor sinful; rather, it is obligatory because it pertains to the preservation and revival of life, which Islam encourages, as Allah Almighty says: "And whoever saves a life, it is as though he has saved all mankind." Saving a life is an obligation for those who are able, and preserving life is one of the five necessities. As for the prayer, you must repeat it after helping the girl.