Officials say the flags will remain at half-mast until sunset on the day the last funeral is held for the victims.
The first service has been set for Jordan Segura on Monday.
Segura was killed at the party early Tuesday along with Lawrence Hong, Josh Hunter, Kaitlin Perras, Zackariah Rathwell — all in their 20s.
The son of a senior police officer, Matthew de Grood, has been charged with five counts of first-degree murder.
People say the party was being held to celebrate the final day of university classes.
The University of Calgary says students affected by the tragedy can defer final exams until May or June.