PORTLAND, Ore. - Veterinarians at the Oregon Zoo are trying to figure out why six cotton-top tamarin monkeys died last Saturday.
The monkeys were part of a group of nine that arrived at the zoo a week ago and were put in a standard 30-day quarantine enclosure.
The zoo expects test results that may show why the monkeys died in a few days.
A zoo veterinarian says it's extremely unusual for six animals that appeared healthy on Friday to turn up dead the next day.
The zoo says the remaining three cotton-top tamarin monkeys appear healthy.