Officials Believe Virus Causing Mass Dolphin Deaths

Hundreds dying on East Coast

Federal officials say a virus is likely what's causing hundreds of dead bottlenose dolphins to wash ashore along the East Coast.

The National Oceanic and Atmospheric Administration says 333 dolphins have been stranded between New York and North Carolina since July 1. That's more than nine times the historical average for the region during July and August.

Earlier this month, NOAA declared an unusual mortality event to provide additional resources to study what's causing the deaths.