The White House described a false inbound missile alert received by Hawaii residents on Saturday morning as an "emergency management exercise," offering no further explanation for the erroneous warning.

"The President has been briefed on the state of Hawaii's emergency management exercise," White House deputy press secretary Lindsay Walters told reporters in West Palm Beach, Fla.

"This was a state exercise," she added.

Hawaiians awoke to alerts on their mobile devices and televisions around 8 a.m. local time Saturday, warning of an "inbound" ballistic missile threat.

"Seek immediate shelter. This is not a drill," the emergency alert stated.

Many residents had already fled to nearby shelters before U.S. Pacific Command confirmed the alert was sent by mistake.

Hawaii Gov. David Ige later told CNN somebody "pushed the wrong button" during an employee shift change, causing the false alert to be sent out.

Trump was visiting his golf course in West Palm Beach, Fla. at the time of the incident Saturday.