Merging of Cells in a Column using OPEN XML

Question

Hi,
 
I have a List which consists of rows in an excel sheet, using those rows I need to merge cells column wise. 
For example, In List I have A,B,C,D columns in each row and List count is 26. I need to merge cells from A6 to A10 and A11 to A15. 
 
Please help me in getting a solution.