Why do people give blood after disasters, but not during blood drives?

It happens after very disaster, whether natural or human-made. Before the floods recede or the crime tape is removed, hundreds will line up to donate their blood. Less than 24 hours after the mass shooting in Las Vegas, a line of people twisted from a blood center around several city blocks. According to one woman's […]Related:Who will take care of Nevada’s wounded psyche?Failure to vaccinate is likely driver of U.S. measles outbreaks, report saysBreast-cancer death rate drops almost 40 percent, saving 322,000 lives, study says
Source: Washington Post: To Your Health - Category: Consumer Health News Source Type: news