Las Vegas Sheriff Joseph Lombardo gave a step-by-step rundown Wednesday night of the response to Monday's shooting.

Key quote: "What we know is Steven Paddock is a man who spent decades acquiring weapons and ammo, and living a secret life much of which will never be fully understood... he meticulously planned the worst domestic attack in United States history."

• 10:05 PM PT: First shots fired by the suspect
• 10:12: Two officers arrive on 31st floor, say shooting coming from directly above them
• 10:15: Last shots fired by suspect (10 minutes after shooting began)
• 10:17: Two officers arrive on 32nd floor
• 10:18: Security officer says he's been shot, gives location of the room
• 10:26-10:30: Eight additional officers arrive on 32nd floor, begin to clear rooms because they don't hear additional gunfire and believe the suspect may have barricaded himself in.
• 10:55: Eight officers arrive in hallway near suspect's room
• 11:20: First room breached, officers notice the suspect is down (75 minutes after shooting began)
• 11:27: Second room breached, no other suspects spotted

Other takeaways:

• Lombardo said he suspected Stephen Paddock likely had an accomplice or accomplices, but that was under investigation.
• He said there was evidence Paddock planned to survive and escape.
• He said Paddock began stockpiling weapons in October 2016, and they were investigating what was going on at that time in his life.