Las Vegas residents are rushing to help the victims of the deadliest mass shooting in modern US history, with hundreds of people queuing for hours to donate blood.

Gunman Stephen Paddock, 64, opened fire at an open-air country music concert in the centre of Las Vegas from the 32nd floor of the Mandalay Bay hotel on Sunday 1 October.

Chaos ensued as thousands desperately ran for cover, hiding under parked cars and behind concession stands.

The massacre claimed the lives of at least 59 people and injured more than 520 others.

Paddock was found dead, armed with 23 guns, after officers stormed the hotel room. His motives for the deadly attack remain unknown, police said, after they searched his home in a quiet residential neighbourhood of Mesquite.

The city's mayor, Carolyn Goodman, asked residents to donate blood as it emerged that hundreds of people had been taken to hospital.

"What we ask for is blood – that's the main thing right now – is that if our people want to do something, and they are healthy, then please donate blood. We'll have plenty of banks available," Goodman said during a news conference.

Hundreds of people queued throughout the night, waiting six or seven hours to donate at banks around the city.

"I'm in line at United Blood Services on Whitney Ranch right now," Kelsey Gunther wrote on Twitter. "The line is about 200 deep."

Shanda Maloney told local broadcaster Kion News that she felt she had to act immediately after hearing the news.

"Hearing all the sirens around, you feel completely helpless," she said. "I just started tweeting 'if you need a ride I'll come pick you up'."

Maloney drove around her neighbourhood, picking up anyone who needed help.

Tales of heroism have emerged from the night, with adults lying on top of young children to shield them from the bullets and people heading back to the concert venue to move wounded victims to safety.

"I would hope that if I or my family, was in a situation like that, that someone would come in and get me," Todd Blyleven told the Washington Post, after he went back to rescue more than 30 people from the gunfire.