Kill all child processes of current Powershell script/session

kill_children.ps1

function KillChildren
{
    Param(
        [Parameter(Mandatory=$True,Position=1)]
            [int]$parentProcessId
    )

    Get-WmiObject win32_process | where {$_.ParentProcessId -eq $parentProcessId} | ForEach { KillChildren $_.ProcessId }
    Get-WmiObject win32_process | where {$_.ParentProcessId -eq $parentProcessId} | ForEach { Stop-Process $_.ProcessId 2>$null }
}

KillChildren $pid

Errors from Stop-Process are ignored in case the process has exited between the query and the call to Stop-Process.

This could be caught out by a child process that keeps spawning new child.