It's at the discretion of the leadership of the organization to decide when it's appropriate to do that. In some incidents it would be very obvious to do, but then there might be some incidents where the leadership and members of the unit would have a sense as to whether something such as that is necessary. However, at all times people are invited to come forward for care, because they might have been exposed to a traumatic incident outside the workplace.
Keeping the door open and encouraging people to seek care for any type of mental health problem is really the way to go, because we treat all mental health issues, not just those related to work.