Officials with the Red Cross and the New York Blood Center say the Los Angeles wildfires and snowstorms on the East Coast have led to what they describe as a concerning decline in blood donations.

The organizations say the decline has put a strain on blood supplies.

The Red Cross says there is an emergency shortage of Type B Negative and O Negative blood.

Type O negative is the universal blood type, meaning it is the most common type used for transfusions where a blood type is unknown.

There is an additional critical need for platelets, which are cells in the blood that form clots to stop bleeding. They are used during surgery, including organ donation and cancer treatments.

Officials encourage people to make an appointment for both donations.

A regular blood donation takes an hour, while the process to donate platelets can take anywhere from two and half hours to three hours.