Image region with sum

Write code which determines whether the sum of all elements in a rectangular area 
in a square 2d array are equal to a target, and if true, prints out the coordinates 
(top left and bottom right) of a rectangular area which has the target sum.

Constraints:
- All elements in the array are positive
- The input array is valid (e.g all rows have the same length)
- If there are multiple solutions, any one is valid, don't need to find all

Example 1:
Input array:
[2, 6, 4]
[8, 3, 1]
[4, 5, 2]
Target:
20

Output:
[1,0], [2,1]
This region sums to 20:
[_, _, _]
[8, 3, _]
[4, 5, _]