A lot of things play into ratios. What state are you in? What age are they kids? How many teachers? Was this all day or at the end of the day? Sometimes classrooms merge at the end of the day.
The ratio for Maryland is 1:3 for infants, 1:6 for two year olds, 1:10 for 3/4 year olds, and 1:15 for 5 and up (although may vary if NAEYC accredited).
Maryland also sets max group size, for example there can be no more than 12 two year olds in one room, no more than 20 3/4 year olds, and no more than 30 kids who are 5 and up in one room. But sometimes this varies depending on the size of the physical classroom.
This is a handbook that contains the ratios, you'll have to scroll down a bit though:
http://www.marylandpublicschools.org/NR/rdonlyres/FF4D42D2-46A0-44E6-9CEC-546C5641F978/31469/Sub16CTRamend012312.pdf
DC and VA may be different, but are probably similar. You can try looking on their licensing page to find out that information. 33 kids in one room does sound like a lot.