I think this came from one of the witnesses:
Brigitte Wolfe, a manager at the Jun Japanese Restaurant in a strip mall across the street from the Planned Parenthood, said six policemen had taken positions in her restaurant and ordered her staff and three customers to stay inside as the scene unfolded across the street.
"We have a bank across the street, so we thought it was a bank robbery, and then all of a sudden we saw SWAT and ATF pull up," she said. "Then we actually had a police officer come to the window tell us to lock the doors and stay away."
http://www.wsj.com/articles/active-shooter-reported-at-planned-parenthood-clinic-in-colorado-1448654443
If it had started out as a bank robbery, there would have been witnesses from inside the bank.
Colorado Springs shooting occurred at Chase Bankby
Colorado Springs shooting that the left originated at a Planned Parenthood actually occurred at a Chase Bank in what sounds like a botched bank robbery.