Alarm when all hosts of a group host goes down

[Sanches]

Hi
Trying out Zabbix for the first time.
Is it possible to define a trigger that will go of if all the hosts of a host group goes down?


Usecase:
5 routers via SNMPv2.
SNMP agent availability item exist.
Trigger will go of if the router has not been responding the last 5 times (5 minute downtime)
If all 5 routers (all host group) does not respond within 60 second, I want alarm directly after one minute.