The American Red Cross is stressing the importance of blood donations for trauma victims this month.
Spokesperson Kristen Stancil said the organization is especially in need of Type O negative and AB blood.
May is Trauma Awareness Month.
Red Cross workers said they face shortages in the summer and winter, which could potentially hurt their ability to help people.
"Every two seconds someone in the United States needs blood," Stancil said. "That blood can only come from volunteers. It can not be manufactured. It can't be made somewhere. So, we do rely on generous volunteers to roll up their sleeves."