Green’s Dictionary of Slang

(orig. US black) a general excl. of alarm, anger, surprise.

1929		S. Ornitz Haunch Paunch and Jowl 115: Al is thundering, ‘Bells, bells, bells! G’wan, try it again.’.
1948		New Yorker 3 July 28: The bebop people have a language of their own [...] their expressions of approval include ‘Cool!’, ‘Gone!’ and ‘Bells, man!’.
1959		Down Beat 30 Apr. 11: This was revelatory for Pres, who usually limited his answers to ‘bells’ or ‘ding dong’.
1989		P. Munro Sl. U.