This is correct. Current estimates place a possible impact event at an energy release of ~7.8 Megatons of TNT. Approximately 500 times the bomb dropped on Hiroshima. Comparable to the Tunguska Event. This is accounting for current size estimates under 100m in diameter.

It is a very serious asteroid. The Tunguska Event could have killed millions of people. The primary reason it didn't was because it happened in the middle of Siberia. The primary witnesses to the devastation were local native groups who still lived that for out, of which there were few. It wasn't properly investigated for over a decade because of the remoteness of where it happened and the low priority as it didn't affect very many people. If that happened over a major city the consequences would be utterly devastating.

It's not K-T Extinction event level, but it is nonetheless quite serious.