first report; initial report; first news
Formal or literary term used in news, official announcements, or written contexts for the earliest information received about an event.
We will inform you as soon as the first report of the accident comes in.
初報では被害は軽微とされていたが、後に大規模な災害と判明した。
The initial report said the damage was minor, but it later turned out to be a large-scale disaster.