It stinks, but the killer left home this morning planning not to return, and the police had to deal with it as best they could.
He didn't tell them directly. He called either a radio station or dispatch and told them he was going to shoot in 10 seconds if the police didn't leave. They weren't able to establish cell contact with him is my understanding, but they were trying to when he started shooting.
They had a megaphone for the negotiator and the perp called a radio station and said to tell police to back off or he would start shooting. Right when the police got the message to clear out...the guy started shooting. THEN they stormed the place.
"but he told them that he was going to count to 10, then start shooting. That's when they broke in."
If that is indeed what he told them - then no- I don't blame them.