How to write two sheets in one book at the same time using openpyxl

I need to create and write a new Excel workbook with about 5 worksheets. The purpose of my code is to read the database and split it into different sheets based on a certain criterion.

I have used the following code in python 2.7 using openpyxl-1.1.0

from openpyxl.workbook import Workbook
dest_filename = 'D:\\Splitted.xlsx'

wb = Workbook()
ws1 = wb.worksheets[0]
ws1.title = 'Criterion1'

ws2 = wb.worksheets[1]
ws2.title = 'Criterion2'

## Read Database, get criterion
if criterion == Criterion1:
    ws1.cell('A1').value = 'A1'
    ws1.cell('B1').value = 'B1'
elif criterion == Criterion2:
    ws2.cell('A1').value = 'A2'
    ws2.cell('B1').value = 'B2'

wb.save(filename = dest_filename)

      

        
        
        
      

    

I can write a separate sheet, but if I try to create a 2nd sheet, I get an "Specify out of range" error in the code ws2 = wb.worksheets [1]

Is there any solution for writing two or more sheets in one book at the same time?