“I am surprised they didn’t kill her and her daughter, too.”
7.62x39 ammo is heavy (more than 6 magazines you feel it) and firing automatic, they would burn through it quickly. The gunmen probably conserved ammo to make sure they had enough for their intended targets. These guys were not amateurs.
Many have said that they attacked like pros with execution shots and moving on to the next target.
No, they had to stay in silent mode until the entered the office on the first floor and went upstairs to the editorial office.
The plan depended on not going loud before that.