The mass killer was no longer shooting after 10:21. This explains why the SWAT team did not blast down the door until 11:21. The extreme urgency had ended. The shooter had stopped firing on hour earlier. It explains why President Trump complemented the Las Vegas Police. From deadline.com:
Why did the gunman stop shooting at 10:21? Because to do so he would have had to turn his back to the door and risk capture or being shot in the back! Had he not been engaged at 13 minutes into the crime, he could have let another 1000 rounds fly into the crowd, and many more could have been killed and injured. If this is true, the two undergunned police and hotel security personnel are extreme heroes!
The automatic weapon the gunman was firing would probably shoot right through the hotel walls. It went through the door.