use Data::Dumper;
@arr = ( [ qw/ 1 2 3 / ],
         [ qw/ 4 5 6 / ] );
print Dumper(\@arr);

# and in your case
@arr[0] = qw/ 1 2 3 /;
@arr[1] = qw/ 4 5 6 /;
print Dumper(\@arr);