When viewing a concern click on  Send Alert To... on the right-hand side underneath Actions

This displays a pop up box that allows you to select the colleague you would like to alert and send them a message: 

Selecting the staff members field will allow you to select either user groups, or by clicking the + next to a user group, individual staff members within a user group:

If required you can then write a message to inform the users why they are receiving this alert. This message is displayed in the email that is sent to them.

It is possible to redact elements of the concern when alerting other people this way.