Why did Moshe address the B'nei Levi?
Rashi and Ramban #1: Refer to 16:7:2:1.
Ramban #2 (citing R. Chananel) and Seforno: Refer to 16:2:3:3.
Oznayim la'Torah (in Pasukf 12): Becuse he saw some Levi'im following Korach.