How can I capture two columns of ls output in a bash script

I want to create a script to delete any directories with numeric groups.

What I have so far captures and analyzes the group:

#!/bin/bash
re='^[0-9]+$'
for x in `/usr/bin/ls -l /var/indexes | sort -k3,3 | tr -s " " | cut -f3 -d " "`
do
if [[ $x =~ $re ]] ; then
   echo "found one $x"
fi
done

The problem is, the actual name of the directory is in another column.

Here is one line of the ls output:

drwxr-sr-x. 3                     3966 root 4096 Oct 20 16:29 dirname

So I need to iterate through the ls results and capture both the group (in this case 3966) and the directory name (in this case dirname) so I can form an rm -rf command to remove it when I find a blank one.

How would I do that?

Thanks in advance.