Chinese state media reported Sunday that they too have discovered an unidentified flying object off its coast and that authorities there were preparing to shoot it down, one day after American and Canadian officials said they downed two such objects over North America.

China’s state-owned Global Times reported that officials in the coastal Shandong province north of Shanghai were warning fishermen in the area to remain vigilant after the object was spotted over waters near the city of Rizhao. The outcome of efforts to shoot it down were unknown early Sunday.

On Saturday, Canadian Prime Minister Justin Trudeau said a U.S. fighter jet acting on his authority shot down an “unidentified object” that was flying high over the Yukon, a day after the United States took similar action over Alaska.

North American Aerospace Defense Command, the combined U.S.-Canada organization that provides shared defense of airspace over the two nations, detected the object flying at a high altitude Friday evening over Alaska, U.S. officials said. It crossed into Canadian airspace on Saturday.

Mr. Trudeau spoke with President Biden, who also ordered the object to be shot down. Canadian and U.S. jets operating as part of NORAD were scrambled and it was an American jet that shot down the object.

Speaking on ABC Sunday, Senator Schumer said the objects shot down by the United States were believed to be balloons, though much smaller than the one shot down off the South Carolina coast last week.

Canadian Defense Minister Anita Anand told a news conference in Ottawa that the object, flying at around 40,000 feet, had been shot down at 3:41 p.m. eastern time, approximately 100 miles from the Canada-U.S. border in the central Yukon. A recovery operation was underway involving the Canadian Armed Forces and the Royal Canadian Mounted Police.

Hours later, in the United States, the Federal Aviation Administration said Saturday night it had closed some airspace in Montana to support Defense Department activities. NORAD later said the closure, which lasted a little more than an hour, came after it had detected “a radar anomaly” and sent fighter aircraft to investigate. The aircraft did not identify any object to correlate to the radar hits, NORAD said.

F-22 fighter jets have now taken out three objects in the airspace above the U.S. and Canada over seven days, a stunning development that is raising questions on just what, exactly, is hovering overhead and who has sent them.

At least one of the objects downed was believed to be a spy balloon from China, but the other two had not yet been publicly identified.

While Trudeau described the object Saturday as “unidentified,” Ms. Anand said it appeared to be “a small cylindrical object, smaller than the one that was downed off the coast of North Carolina.” A NORAD spokesman, Major Olivier Gallant, said the military had determined what it was but would not reveal details.

Ms. Anand refused to speculate whether the object shot down over Canada came from China.

“We are continuing to do the analysis on the object and we will make sure that analysis is thorough,” she said. “It would not be prudent for me to speculate on the origins of the object at this time.”

Ms. Anand said to her knowledge this was the first time NORAD had downed an object in Canadian airspace.

“The importance of this moment should not be underestimated,” she said. “We detected this object together and we defeated this object together.”

She was asked why an American jet, and not a Canadian plane, shot the object down.

“As opposed to separating it out by country, I think what the important point is, these were NORAD capabilities, this was a NORAD mission and this was NORAD doing what it is supposed to do,” she said.

Ms. Anand didn’t use the word “balloon” to describe the object. But later, General Wayne Eyre, chief of the defense staff, said the instructions given to the planes was “who ever had the first, best shot to take out the balloon had the go-ahead.”

Mr. Trudeau said Canadian forces would recover the wreckage for study. The Yukon is westernmost Canadian territory and the among the least populated part of Canada.

After the airspace closure over Montana, multiple members of Congress, including Montana Senators Daines and Tester, said they were in touch with defense officials. Mr. Daines tweeted that he would “continue to demand answers on these invasions of US airspace.”

Just about a day earlier, White House National Security Council spokesman John Kirby said an object roughly the size of a small car was shot out of the skies above remote Alaska. Officials couldn’t say if it contained any surveillance equipment, where it came from or what purpose it had.

Mr. Kirby said it was shot down because it was flying at about 40,000 feet and posed a “reasonable threat” to the safety of civilian flights, not because of any knowledge that it was engaged in surveillance.

According to U.S. Northern Command, recovery operations continued Saturday on sea ice near Deadhorse, Alaska.

In a statement, the Northern Command said there were no new details on what the object was. It said the Alaska Command and the Alaska National Guard, along with the FBI and local law enforcement, were conducting search and recovery.

“Arctic weather conditions, including wind chill, snow, and limited daylight, are a factor in this operation, and personnel will adjust recovery operations to maintain safety,” the statement said.

On February 4, American officials shot down a large white balloon off the coast of South Carolina.

The balloon was part of a large surveillance program that China has been conducting for “several years,” the Pentagon has said. The United States has said Chinese balloons have flown over dozens of countries across five continents in recent years, and it learned more about the balloon program after closely monitoring the one shot down near South Carolina.

China responded that it reserved the right to “take further actions” and criticized the United States for “an obvious overreaction and a serious violation of international practice.”

The Navy continued survey and recovery activities on the ocean floor off South Carolina, and the Coast Guard was providing security. Additional debris was pulled out Friday, and additional operations will continue as weather permits, Northern Command said.