CHICAGO (WLS) --Tuesday is World Blood Donor Day, and the nightclub massacre is just one reason the need is so great.
There's an urgent need for all blood types, but especially the universal blood types: O-negative, O-positive and AB plasma.
Lifesource in Chicago shipped blood to Orlando on Sunday, right after they learned about the tragedy and as their blood bank in Florida reached capacity and could not take any more donors.
So now Lifesource needs to replenish its supplies.
Lifesource said blood donations are traditionally lowest in the summer months, and that's when the need for blood usually increases.
Appointments are recommended but walk-ins are welcome.