A Louisiana senator has advised citizens to "lock your doors" following a classified briefing to lawmakers on the unidentified objects shot down over the weekend.

Four objects have been shot down over North American airspace since February 4. The first was identified by the Pentagon as a Chinese surveillance balloon, but the U.S. Defense Department has not confirmed the nature of the remaining three objects. Intelligence officials are "considering as a leading explanation that these could be tied to commercial or research entities and benign," the White House said on Tuesday.

Senators received a classified briefing on Tuesday. It was delivered by officials from the Defense Department, NORAD (North American Aerospace Defense Command), and the United States Northern Command, as well as the Office for the Director of National Intelligence.

Speaking to the media following the briefing, Louisiana Senator John Kennedy said officials had so far been unable to locate the remnants of the three unidentified objects, excluding the spy balloon.

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