A Washington state woman became the first U.S. fatality due to measles in more than a decade, and a recent measles outbreak was likely to blame, health officials said.

The woman's cause of death was pneumonia due to measles, and the measles infection was discovered at her autopsy, a public health agency said.

She was most likely exposed to measles at a local medical facility during an outbreak in Clallam County in Washington, according to a statement Thursday from the Washington State Department of Health. She was also on medication and had several other health conditions "to a suppressed immune system," according to a statement.

Washington has had 11 cases of measles, and the last active case was reported in late April.

"Within about three weeks of exposure to someone with measles, it's possible to develop the disease," according to the public health agency. "Since more than three weeks has already passed since the last active measles case, no one who had contact with one of the known cases is any longer at risk for developing measles from those exposures."

Health officials recommended that children be vaccinated with two doses of the measles vaccine, with the first dose between 12 and 15 months.

An outbreak of measles last year emerged in Disneyland and has spread to several states.