def METHOD_NAME(group_id):
    if not Group.find_by_id(group_id):
        raise ApiError('not found', 404)
    group_users = GroupUsers.find_by_id(group_id)
    if group_users:
        return jsonify(
            status='ok',
            users=[user.serialize for user in group_users],
            total=len(group_users)
        )
    else:
        return jsonify(
            status='ok',
            users=[],
            total=0
        )