(CNN)The Pacific Northwest heat wave in late June was a mass casualty event, officials said. Hundreds of people likely died in the multi-day, record-breaking heat, and the death toll continues to rise.

At least 83 people died from heat-related illness in Oregon, and officials are investigating another 32 deaths. In Washington, at least 78 people died. Across the border in British Columbia, officials counted nearly 800 deaths from June 25 to July 1 — 500 more than normal for that time period and which they believe are tied to the heat, according to Lisa Lapointe, the chief coroner for the province. In reality, it could be months before we know the final toll.

Despite the staggering statistics, there was no obvious sense of urgency around the tragedy as it played out — nothing similar to a hurricane making landfall, a gunman opening fire in a night club or a wildfire destroying a town. They were hundreds of quiet deaths from an invisible disaster: unprecedented heat, which dozens of scientists concluded was “virtually impossible” without climate change.