Cherokee National Attorney General Todd Hembree and other officials are attending the expo.
Hembree said he was staying just one floor above the shooter Sunday night at Mandalay Bay.
He said he knew something was wrong when he saw tons of first responders and a police helicopter shining through the windows of hotel.
Hembree said around 3 a.m. SWAT team members came into his room looking for other suspects.
"It was a surreal experience knowing that an American tragedy was happening all around you," said Hembree.
Hembree said other Cherokee Nation officials have returned home safety on Monday to Oklahoma.
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