(National Weather Service)

(This article, originally published Wednesday afternoon, was updated Thursday based on a new statement from the National Weather Service.)

It came without warning. As workers were busy preparing forecasts and alerts at a National Weather Service center in Maryland on Wednesday morning, they were suddenly interrupted by a message in Chinese piped over the building’s intercom.

The voice was a woman’s, which also reached building employees via phone at the National Oceanic and Atmospheric Administration’s Center for Weather and Climate Prediction in College Park, Md.

On Wednesday afternoon, Weather Service officials scrambled to understand the source of the audio intrusion.

“We are aware of the Chinese message that is propagating through the phone system and was [broadcast] over the building PA,” read an email from Doug Fenderson, the branch chief for infrastructure and Web services at the center, sent at 12:50 p.m. “We are engaging the Vendor AT&T to alert them of the incident and get root cause. The phone [system] is not tied to any of the Government IT controlled systems in the building. Please do not be alarmed.”

A Weather Service employee, speaking on the condition of anonymity, said the phone message came about 15 minutes before the intercom message. Both messages lasted about 45 seconds. The employee said nothing else out of the ordinary had happened at the center Wednesday.

The intercom message, translated from Chinese, said something to the effect of “you have a package from Amazon at the Chinese Embassy, press 1 for more details,” the employee said.

The audio took employees by surprise since the building-wide intercom is seldom used, two building occupants said. They could recall hearing sound over the intercom only during shelter-in-place or fire drills.

In a statement published Thursday, NOAA said the intrusion was the result of a “a series of robocalls” which reached both desk phones at the Weather Service center and its public address system. “This robocall, with a female Mandarin recording, has been warned against for some time and is a known issue in the United States,” the statement said.

NOAA pointed to an April blog post from the Federal Trade Commission that notified the public about the scam. “Have you gotten a call from someone saying they’re from a Chinese Consulate office?,” the blog post begins. “If so, you’re not alone – based on reports to the FTC and the real Chinese Consulates. But here’s the thing: it’s not a Chinese Consulate office calling. It’s a scammer.”

The NOAA statement said its information technology team worked with its phone vendor “to prevent all outside telephone numbers from accessing the building’s PA system, to prevent this from occurring again.”