DALLAS -- The American Red Cross is asking people nationwide to donate blood and platelets after the tragedy in downtown Dallas that left five police officers dead.

“Our hearts go out to all those who are affected by this tragedy. In response, the American Red Cross has supplied more than 225 blood products to one of the hospitals treating victims of the shooting and we are on standby should additional blood be needed," Anita Foster said.

There is an emergency need now for blood and platelet donors nationwide, Foster says.

"Yesterday’s tragedies illustrates that it is the blood already on the shelves that helps during an emergency. The Red Cross is grateful for all donors who generously give blood throughout the country."

To find locations where you can donate, go here.