Please pay close attention. This is an urgent message from [XXX].
Officials [emergency, public health, etc.] believe there has been a serious incident [describe incident including time and location] in xxx area.
At this time, we do not know the cause or other details about the incident.
Local officials are investigating and will work with State and Federal officials to provide updated information as soon as possible.
Stay informed and follow the instructions of health officials so you can protect yourself, your family and your community against this public health threat.
Give specific information about when and how the next update will be given
When more information is known, additional messages could be added about what is happening, the specific terrorist agent, the actions people should take to protect themselves and others and where to go for more information. Since these messages were developed to be effective for a variety of scenarios, they will need to be adapted to the specific event.