COEUR d'ALENE — It's times like these — the aftermath of the deadliest mass shooting in modern U.S. history — that reaffirm why Donald Croffler donates blood.

"I was raised that you give back to the community," the Coeur d'Alene man said Tuesday while donating blood to the Inland Northwest Blood Center in Coeur d'Alene. "It's never about you. It's about helping other people."

Only about 6 percent of the population has Croffler's blood type — O-negative — but it’s in the highest demand during traumatic situations because it is universal.

The INBC sent 50 units of O-positive blood and five units of O-negative to Las Vegas on Monday in response to Sunday night's shooting at the outdoor Route 91 Harvest Festival near the Mandalay Bay Resort and Casino that killed 59 people and injured more than 520 others.

"Our community is making a huge difference," said Michael Long, recruitment manager for INBC. “We’re trying to accommodate as many walk-in donors as we can, but it’s best to make an appointment to make sure we can get people out in a timely fashion.”

Long said since the shooting, the center has seen about double its average number of donors. On a typical day the center sees 15 to 20 donors.

"The increase is definitely because of the awareness with the Las Vegas situation," he said.

Long said the center has brought on additional staff to try to accommodate the spike in blood donations.

"The immediate needs are for O-negative, O-positive and platelet donations," Long said. "However, donors of all types will be needed to replenish the supply."

He said the natural reaction during a crisis is to want to donate blood as soon as possible, but donations every day help.

"Even if you're scheduled next week, it could replenish what has been used or shipped to Las Vegas or take care of our local needs," Long said. "The need is always there, so we try to have people become lifelong donors who donate three or four times a year. We always need to make sure we are ready to roll."

Coeur d'Alene's Wayne Longo, former police chief, was among the donors at the center on Tuesday.

"If I hadn't been scheduled, I would have come in in a heartbeat," he said, referring to the Vegas aftermath.

Longo said he's been donating blood at the center for about 20 years and the only other time he can recall the center having to turn away walk-in donors because they couldn’t keep up was after the Sept. 11, 2001, terrorist attacks.

"There's always a need (for blood donations), so the hope is that people will make an appointment," Longo said.

Longo said he saw a lot of tragedies during his law enforcement career, but struggles to comprehend the ever- increasing, often random mass incidents of today.

"It's shocking," he said. "So many lives are affected."

Longo was quick to recognize that he and the accused shooter, 64-year-old Stephen Paddock of Mesquite, Nev., are the same age.

INBC is part of United Blood Services, a nationwide network of blood centers. That network allows the local center to move lifesaving blood donations around the system to where it's most needed.

"We are in communication with hospitals in that area to assess additional blood needs and stand ready to provide additional support," Long said.

Long said it is the blood on hospital shelves that saves lives.

"That's why it's crucial we constantly replenish the supply so that we're ready for tragic situations like the shooting in Las Vegas," he said.

Many other relief efforts are underway.

An online GoFundMe benefit account for the victims raised nearly $3.5 million in 24 hours. The FBI's Victim Services Division, meanwhile, is providing emergency assistance and counseling to the victims.

Croffler said seeing people make a difference builds strength in such times of need.

"It's all about the community taking care of each other," he said.