If you feel hopeless today after waking up to news of the mass shooting in Las Vegas, you are not alone. The shooting, which was the worst mass shooting in modern U.S. history, has ended the lives of at least 50 people and injured another 400. Due to the large scale of the attack, hospitals across the state are putting out calls for blood donors — and that’s where you can help.

Nevada hospitals, as well as the city’s sheriff, are asking people in the state to donate blood. Even if you live outside of Nevada, donating blood can still help those injured, as blood is often sent to places in need after tragedies and natural disasters.

If you're in Las Vegas and want to be a hero — donate blood. They're desperate for supply to save lives. Here's where to go: pic.twitter.com/DBU86yQtmY — Alheli Picazo (@a_picazo) October 2, 2017

Come to 6930 W. Charleston Rd to donate blood to all of our Las Vegas family ❤️❤️ pic.twitter.com/EdpLqUyeX3 — Christina Lombardi (@c_lombardii) October 2, 2017

#VegasStrong: Lines to donate blood were out the door this morning in Las Vegas https://t.co/qpKoTdlLA8 pic.twitter.com/M6A8O0sb3H — ABC7 Eyewitness News (@ABC7) October 2, 2017

As a nurse in one of the Las Vegas' ER's this evening there are 2 things you can help us with..donate blood if you are able tomorrow & pray. — ????Sharon Murphy???? (@sharonainvegas) October 2, 2017

We desperately need blood at the United Blood Center at 6930 W Charleston and 601 Whitney Ranch Dr. in Henderson. — Steve Sisolak (@SteveSisolak) October 2, 2017

This. Is. Vegas.

This is our community.

These are our people.

Thank you to everyone here donating.#PrayForVegas #VegasShooting pic.twitter.com/wn5RA5jVLX — Shanda (@shanda) October 2, 2017

To donate, you must be 17 years of age (16 with parental consent) and weigh at least 110 pounds. If you are concerned your health prevents you from donating blood, you can learn more about the restrictions and requirements here. Once at the blood center, you will fill out a questionnaire and be screened by staff. If you are ineligible, staff at the blood donation center will let you know before you donate. For your health, be sure to hydrate and eat before giving blood.

To find a blood donation center near you, visit United Blood Services.

Header image via Shanda/Twitter.