The gunfire erupted Thursday morning at the Vista Del Valle complex, police said, just blocks away from the Rio All-Suite Hotel & Casino, where the World Series of Poker's final table is played every summer.
In surveillance video released by Las Vegas Metropolitan Police, suspect Robert Thomas can be seen approaching a male and female worker inside the management office.
Thomas then pulls a gun out of his jacket and fires one round toward the back of the room, missing another employee and striking a computer, police said.
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After allowing the female employee to leave, Thomas allegedly shot the male worker in the lower body at point-blank range. The victim was sitting in a chair and crumpled to the ground, in the disturbing footage.
As the wounded employee writhed in pain on the ground, Thomas allegedly walked up to him and fired one more round into his leg.
Moments later, responding officer Ronald Hornyak fired one shot through the office door at Thomas, shattering glass, LVMPD body-camera video showed.
The bullet traveled through Thomas' lapel but didn't strike the suspect, before officers threw the suspect to the ground and arrested him, Assistant Sheriff Brett Zimmerman said.
Moments before officers confronted Thomas, Hornyak could be heard in body camera footage: "Shots still being fired. We got to make entry."
Zimmerman credited officers acting quickly to subdue Thomas, rather than wait for backup.
"They heard the shot and the key was the officer told this partner they had to make entry due to the possibility of any more people being injured or killed while inside that apartment complex office, not knowing what they had," Zimmerman said.
Thomas was upset with the apartment complex about water damage in his unit, police said.
The wounded maintenance worker will survive and Thomas was treated for cuts from the shattered glass, officials said.
The nonagenarian suspect was booked on suspicion of attempt murder, kidnapping, discharge of a firearm indoors, burglary and carrying a concealed weapon. Thomas had no previous criminal record, police said.
David K. Li
David K. Li is a breaking news reporter for NBC News.