Meticulous Planning by Las Vegas Gunman Before He Opened Fire:

Before he mowed down concertgoers from a perch high in a hotel tower, Stephen C. Paddock created a ring of surveillance around him, with video cameras in his suite and in the hallway, law enforcement officials said on Tuesday. But investigators were still at a loss to offer a motive for the massacre.

The cameras — apparently intended to warn of approaching threats — along with the 23 guns, hundreds of rounds of ammunition, and other equipment found in the gunman’s hotel suite, suggested a thought-out plan to have plenty of time to wreak carnage while holding the police at bay.

And:

Twelve of the rifles Mr. Paddock had in his luxury suite on the 32nd floor of the Mandalay Bay Resort and Casino were outfitted with a “bump stock,” a device that enables a gun to fire hundreds of rounds per minute, like a machine gun, which may explain how he was able to rain such devastation on the crowd below, law enforcement officials said. Such devices are generally legal, and the possibility that he may have used them set off a fresh round of calls by Democratic lawmakers in Washington to pass more gun regulations after the tragedy.

Paddock didn’t have a criminal record so he flew under the radar of the FBI.

So if we can’t preemptively spot terrorists, then we need to do something else. We need to update our gun laws in the United States.

Preventative measures are much better than reactive treatments.