Taiwan's top military officer and seven others died after a helicopter crash landed in the mountains Thursday, the defence ministry said.
President Tsai Ing-wen, who is seeking reelection, has cancelled her campaign activities for Thursday to deal with the crash. Tsai and her Democratic Progressive Party are now ahead in the polls, leading main opponent Han Kuo-yu of the Kuomintang party.
"We are investigating whether (the cause) was environmental or mechanical", he told reporters. Just over 10 minutes later, it dropped from the radar screen and went down in the mountainous, heavily forested Wulai area southeast of the capital.
Shen, 62, and several top military officials were on a routine mission to visit soldiers in the northeast Yilan county ahead of the lunar new year later this month. Helicopter was previously reported missing.
Photos from the scene showed the mangled helicopter amid broken tree trunks on a foggy hillside.
But while there were survivors, three people were still missing including the air force general Shen Yi-ming, the island's chief of the general staff.
China considers Taiwan to be a breakaway province and, under leader Xi Jinping, has been making increasingly aggressive suggestions about using force to "reunify" the country, although Taiwan has never been part of the Communist-ruled People's Republic.
Alexander Huang, a strategic studies professor at Tamkang University in Taiwan who had known Shen for a decade, said he had stood out as a pilot and an officer.
This is not the first time that a United States-manufactured Black Hawks chopper has crashed in Taiwan.
The Black Hawk helicopters are among the American military equipment sold to the self-ruled island, to help it maintain independence from mainland China.