Blood donations are at an all-time low in New York City in a situation the New York Blood Center calls "critical."

Elizabeth Castro, with the New York Blood Center, says that the number of donations they have received recently has plummeted. She says they need to collect around 2,000 pints of blood a day to supply more than 200 hospitals in the tristate area.

"Don't assume you can't give blood for medical reasons, traveling-related reasons," says Castro. "Come to the blood center or to the blood drive and let them determine whether or not you can give blood."

In an effort to straighten out those numbers, it hosted a drive at Fordham High School Tuesday.

The need for donations is constant -- one reason for that is because blood actually expires after a limited amount of time. Officials say a donation only takes an hour, and a single donation can help save multiple lives. No appointments are needed, and you can donate every 56 days.

Castro says a diverse donor pool is necessary because not only does blood need to be a precise match, it also has to match ethnicity.