sort and join (in group) in array

Hopefully, I can explain this correctly...

I have a multidimensional array and am trying to group them according to the value of one the keys.

input table:

Array
(
    [0] => Array
        (
            [0] => Kiynf
            [1] => sort1
            [2] => extraPar1
        )

    [1] => Array
        (
            [0] => Lwbyg
            [1] => sort1
            [2] => extraPar1
        )

    [2] => Array
        (
            [0] => HOUpe
            [1] => sort2
            [2] => extraPar1
        )

    [3] => Array
        (
            [0] => iSPtD
            [1] => sort2
            [2] => extraPar1
        )

    [4] => Array
        (
            [0] => NVXkO
            [1] => sort2
            [2] => extraPar1
        )

    [5] => Array
        (
            [0] => uRZFv
            [1] => sort2
            [2] => extraPar1
        )

    [6] => Array
        (
            [0] => ZLGMo
            [1] => sort2
            [2] => extraPar1
        )

    [7] => Array
        (
            [0] => 5dEQl
            [1] => sort3
            [2] => extraPar1
        )

    [8] => Array
        (
            [0] => lnEeg
            [1] => sort3
            [2] => extraPar1
        )

    [9] => Array
        (
            [0] => AO5Eo
            [1] => sort3
            [2] => extraPar1
        )

    ...

)

and i want to, get array like this:

Array
(
    [0] => Array
        (
            [group] => Kiynf | Lwbyg
            [1] => sort1
            [2] => extraPar1
        )


    [2] => Array
        (
            [group] => HOUpe | iSPtD | NVXkO | uRZFv | ZLGMo
            [1] => sort2
            [2] => extraPar1
        )

    [3] => Array
        (
            [group] => 5dEQl | lnEeg | AO5Eo
            [1] => sort3
            [2] => extraPar1
        )

   ... 

pls help