Assign parallel task to multiple groups and users

Hi,

I have an interesting query: How can I have a human task be assigned and completed in a parallel way by a number of selected groups and/or users?

The idea is that the initiator would select a list of groups and specific users to assign a Human Task step to. Each group/user needs to be able to complete their copy of the task simultaneously to the others. The task should only be completed once everyone assigned has completed it.

Thanks in advance.