Up-and-coming country star Luke Combs had just started his set on the smaller of the two festival stages when Kody Robertson, an auto-parts salesman from Columbus, Ohio, squeezed in at the end of the bar next to Michelle Vo, an insurance agent from Los Angeles.

The 32-year-olds connected immediately. They joked about their mutual love of golf. He recommended new beers for her to try as she showed him the large floral tattoo covering much of her back. They realised that they were both staying at the Luxor.

A longtime country music fan, Robertson was in Las Vegas with a group of friends and told Vo about the fun they'd had at last year's Route 91 Harvest festival. Vo replied that she'd only recently fallen for the genre. This was her first festival, and she was here alone. By the time the night's final act took the main stage, the fast friends had settled into a spot about 20 yards from the right side of the stage, nestled between a few cuddly married couples and a rambunctious bachelorette party.

Then the first shots were fired.

It was 10.08pm. Robertson and Vo searched the air for the fireworks they assumed they were hearing. Then came a second burst: indiscriminate gunfire hailing from a 32nd-floor window at the Mandalay Bay Resort and Casino.

Screams punctuated the pop-pop-pop. Jason Aldean, the headline act, ran from the stage. A bullet pierced the left side of Vo's chest.

"She got hit and I turned and saw her immediately fall to the ground," Robertson recalls. "She was literally right beside me, maybe two feet away."

Robertson threw his body on top of hers as a shield from the bullets and, when the firing finally seemed to stop, worked with another man to carry Vo out of the venue - pausing for cover each time the gunfire resumed.

Sunday night's massacre in Las Vegas - the deadliest mass shooting in modern American history - left at least 58 people dead and 527 injured. It was a scene of romance and carefree revelry, an occasion meant to be shared with loved ones and foster new friendships.

That scene turned tragic when a hail of hundreds of bullets came down on the open field, prompting many to shield the people closest to them - often relatives, best friends, spouses and in some cases, new companions.

Among the countless couples swaying in the crowd of 22,000 people were Bobby and Jenny Parks, high school sweethearts from Lancaster, California.

When the gunshots began and Jenny fell to the ground, Bobby thought Jenny had fainted, his uncle Steven McCarthy later recalled. Then, realizing what was happening, he covered her with his own body. He felt the blood. His wife of 15 years had been shot in the head.

Jenny was hit a second time, the bullet travelling through her body and striking Bobby in the arm.

She died as he held her.

Elsewhere on the field, Jack Beaton, 54, of Bakersfield, California, was telling his wife "I love you, Laurie," for the last time as gunfire erupted around them. They'd come to the concert as a celebration of their 23rd wedding anniversary.

"I love you too," Laurie, 49, declared back.

Then the bullet struck. Beaton died in his wife's arms.

Robert Eardley of St. George, Utah, was trying to save his boyfriend, Cameron Robinson, carrying him through the crowd in search of a vehicle that could take him to the hospital. Robinson had recently moved into Eardley's house, even though it meant his daily commute to work would be more than 100 miles.

He had wanted to make sure they were together. Robinson died before reaching a hospital.

Carrying his new friend through the same crowds, Robertson spotted a white pickup truck whose driver was headed to a hospital. He set Vo down on the truck bed then ran back toward the stage.

Clusters of bodies lay crumpled on the ground as bullets dinged the metal roof of the bar near the back of the venue.

In the heartbeats between rounds, Robertson and other would-be rescuers ran from person to person, checking pulses and pulling bleeding bodies to safety.

"We put a girl on a beer cooler to try to push her out; we were carrying people out on the steel barriers from the perimeter," Robertson said. "Wives screaming at husbands to wake up, and a husband on top of his wife trying to do CPR."

Then he saw it: Vo's purse, on the ground near where they'd been dancing.

Her phone wasn't inside, so he furiously called the number Vo had given him earlier until, finally, someone answered. Another group of concert-goers had found the phone as they ran for the exits. Robertson could pick it up at Planet Hollywood.

By the time he retrieved it, Vo's phone was full of frantic text messages and voice mails, which he couldn't open without her passcode.

The blood covering his jeans and arms had begun to dry a dark crimson when Vo's phone buzzed again in the early morning hours.

"Please tell me that she's OK," Jeremiah Hawkins, 37, the husband of Vo's oldest sister, begged through the phone.

Robertson relayed what he knew: She had been shot in the chest and taken to a hospital. He'd keep going to hospitals until he found her. He promised.

At Sunrise Hospital, Robertson described Vo to the worker behind the front desk.

Five-foot-three. Asian. Dark Hair. A big flower tattoo on her back.

She might be here, the hospital worker told Robertson, before pointing him to the auditorium where the families and friends of the unaccounted for were gathered. Doctors and counsellors and police officers trickled in and out with updates. Someone brought in a comfort dog for those in need of something to hold. Every 20 minutes or so, another family received their news. More often than not, it seemed, the news was not good.

As the early morning stretched toward lunch, the once-animated emotions on the faces of the three dozen or so still waiting gave way to sullen stares. Some paced. Others rocked. A few prayed. Robertson ate a doughnut. The coffee went cold.

The news came about 11am. Three women from the hospital - two doctors and a counselLor - led Robertson to a small back office.

"Michelle didn't make it," one of the doctors said. "The wounds were too much. She didn't make it."

Robertson called Hawkins, told him he should sit down, and then put the phone on speaker. The doctor said it again.

"She didn't make it."

When he tearfully emerged from the front doors, those waiting outside the hospital - many of them family members of the wounded - embraced him in a tight hug. A man came up to ask if Robertson was all right. Another came up and prayed with him. For a moment, he felt comfort. Soon, it was gone.

"That's when it hit me," Robertson said. "I didn't really want to talk to anyone."

He looked down at his phone, its screen still covered in blood. Four-and-a-half miles to the Luxor. Robertson started walking.

He was supposed to depart Monday, but Robertson is still in Las Vegas.

His boss in Ohio told him to take all the time he needs. Southwest Airlines let him change to a later flight. The Luxor extended the stay on his room.

Las Vegas shooting – in pictures Show all 15 1 /15 Las Vegas shooting – in pictures Las Vegas shooting – in pictures People scramble for shelter at the Route 91 Harvest country music festival after gun fire was heard Getty Las Vegas shooting – in pictures People carry a person at the Route 91 Harvest country music festival after shots were fired David Becker/Getty Las Vegas shooting – in pictures People run from the Route 91 Harvest country music festival after gun fire was heard David Becker/Getty Las Vegas shooting – in pictures A handout photo released via Twitter by Eiki Hrafnsson (@EirikurH) showing concertgoers running away from the scene (C) after shots range out at the Route 91 Harvest festival on Las Vegas Boulevard EPA/Eiki Hrafnsson Las Vegas shooting – in pictures People lie on the ground at the Route 91 Harvest country music festival after hearing gun fire Getty Las Vegas shooting – in pictures A man in a wheelchair is taken away from the Route 91 Harvest country music festival after hearing gun fire David Becker/Getty Las Vegas shooting – in pictures People stand on the street outside the Mandalay Bay hotel near the scene of the Route 91 Harvest festival on Las Vegas Boulevard EPA/Paul Buck Las Vegas shooting – in pictures FBI agents confer in front of the Tropicana hotel-casino after a mass shooting during a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Las Vegas police run by a banner on the fence at the Route 91 Harvest country music festival grounds after shots were fired David Becker/Getty Las Vegas shooting – in pictures An injured person is tended to in the intersection of Tropicana Ave. and Las Vegas Boulevard after a mass shooting at a country music festival Ethan Miller/Getty Las Vegas shooting – in pictures Metro Police officers pass by the front of the Tropicana hotel-casino after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip AP/John Locher Las Vegas shooting – in pictures A cowboy hat lays in the street after shots were fired near a country music festival in Las Vegas Getty Las Vegas shooting – in pictures Las Vegas Metro Police and medical workers stage in the intersection of Tropicana Avenue and Las Vegas Boulevard South after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Sheriff Joe Lombardo (2-R) speaking during a press briefing in the aftermath of the active shooter incident on Las Vegas Boulevard EPA

The hotel also extended Vo's room so that her family members would have time to retrieve her belongings. They landed Monday afternoon - a sister, a brother-in-law, some friends - and quickly made their way to the south tower, Room 11375, where Robertson was staying.

"Kody was our guardian angel," said Diane Hawkins, 40, Vo's oldest sister, who believes that had Robertson not tracked down her sister, their family would still be searching for her. "He refused to let her be alone."