LIMA -- Environmental officials are investigating the deaths of over 800 dolphins that have washed up this year on the northern coast of Peru. According to Peruvian Deputy Environment Minister Gabriel Quijandria, an outbreak of Morbillivirus or Brucella bacteria may have been behind the deaths. In talks with CNN, Quijandria said he expects the results of the test to be available within the week. On Thursday, Quijandria said a total of 877 dolphins washed up in a 137-mile area stretching from Punta Aguja to Lambayeque. Over 80% of the dolphins were already in the advanced state of decomposition, making it hard to study their deaths. The Peruvian government formed a panel from various ministries to study a report by the Peruvian Sea Institute (IMARPE). Authorities concluded that the dolphins' deaths were not caused by lack of food, biotoxin poisoning, interaction with fisheries, poisoning with pesticides or contamination by heavy metals. The mass death of dolphins in Peru marks the third set of strandings in about two months. In February, 179 dolphins washed ashore in Cape Cod, in eastern United States. Marine biologists are still trying to identify the cause of death of 108 of those dolphins. In March, a video footage shot from a beach in Rio de Janeiro showed over 30 dolphins on shore. Luckily, all dolphins were returned safely to sea.