LAS VEGAS – When Jennifer Tobin, an internet technologies architect from Phoenix, Arizona, checked into the Mandalay Bay hotel in Las Vegas, Nevada, on Oct. 1, she wasn’t expecting anything more than the usual week of gambling and attending a convention for IT professionals.

Arriving at around 5 p.m. and eating, playing the slot machines and mingling with peers in attendance for the NetApp Insight Conference, Tobin decided to go to her 23rd-floor room for the night, rather than see the sights of Vegas’s famous Strip.

“I had a sinus infection and wasn’t feeling well,” remembers Tobin.

Unbeknownst to Tobin, and other guests of Mandalay Bay, at approximately 10:05 p.m., on the opposite side of the building, from a room on the 32nd floor, Mesquite, Nevada, resident Stephen Paddock began opening fire on a concert crowd below with bump-fire assisted rifles, ultimately killing 57 people and injuring 498, according to police reports. The gunman killed himself before authorities could arrive.

At around 10:20 p.m., Tobin heard sirens and helicopters.

“The first thing I thought was ‘Man, the windows must be insulated really badly,’” said Tobin, who went to the window, facing the hotel’s pool to the south, only to see dozens of emergency vehicles and flashing lights clogging the streets behind Mandalay Bay.

Turning the television to a local news station and getting on her computer, Tobin soon learned, through Facebook, that the hotel was involved in a mass casualty event, possibly with a live shooter.

“I posted a message to let everyone know I was OK, then I got away from the window,” said Tobin.

Using Facebook’s mass events feature, Tobin was able to keep track of what was happening, even though the hotel never indicated to her or other guests that there was a shooting, or that they were on lockdown.

“The hotel has two in-house TV channels and a telephone service and never once did anyone notify us of what was happening,” said Tobin. “I would be really interested in seeing MGM’s disaster plan.”

After packing her bags in case of evacuation, Tobin stayed up and monitored the event via social media and television. “Social media was very helpful, but also very cruel because of all the speculation and made up stuff,” said Tobin.

At one point, Tobin was contacted by a colleague, who had been placed under lockdown in a neighboring hotel.

“By this time, the Strip had been totally shut down,” remembers Tobin.

At 3:30 a.m., Tobin heard Las Vegas police in the hallway, announcing themselves.

“Two S.W.A.T. [Special Weapons and Tactics] officers came to my room and checked the bathroom and behind the curtains before they went to clear the rest of the rooms on our floor,” said Tobin.

Learning that the lockdown had been lifted at 8:30 a.m. on Oct.2, (again, via social media) Tobin ventured down to the lobby of the hotel to check in with her conference and to learn if it had been cancelled.

“It was really eerie,” said Tobin. “There were still drinks and food on all of the tables and the casino was shut down and dark, which is really creepy for Las Vegas.”

Although Tobin’s conference was rescheduled to start on Oct. 3, the mood inside MandalayBay had changed noticeably.

“There were police dogs literally everywhere, and police all over Vegas Boulevard,” said Tobin.

While she never saw the scene of the concert shooting, Tobin did see victims streaming into the hotel throughout the day.

“You could just tell by the looks on their faces that they had been there,” remembers Tobin, who rode up the elevator with two young women, barefoot and clutching their cowboy boots, who were left traumatized by the event.

“They were staying in the room across from mine and when they got to the door, they just started shaking and crying,” said Tobin.

Tobin was immediately struck by the outpouring of donations immediately after the event, with people immediately rushing to donate blood.

“They had to turn people away because they had so many donations.”

When Tobin finally got tired of the constant news updates and rising death toll playing out on television, she went down to the casino to try to find some normality.

“Workers had returned and the casino was back to normal but there weren’t many people there,” said Tobin. “I sat down to play a video poker machine and heard a voice behind me, which was the voice of Homer Simpson coming from one of the machines, and I thought, “you know … this isn’t right’.”

Finishing her conference and returning to Phoenix, Tobin has had time to reflect on the tragedy that occurred, and the aftermath.

“My takeaway is that there’s evil in the world and you just have to actively try to promote good,” said Tobin.