The chief of the general staff, Shen Yi-ming, was among eight senior officers -- including three major generals -- who died when their Black Hawk helicopter smashed into mountains near Taipei.

The 62-year-old general and his entourage were on a routine mission to visit soldiers in northeast Yilan county when the incident happened.

"Five have survived while the other eight of our colleagues on board were killed. We are deeply saddened ... and give our condolences to their families," Air Force Commander Hsiung Hou-chi told reporters.

President Tsai Ing-wen's office announced that she will cancel all campaign activities for three days after the tragedy.

"As commander-in-chief President Tsai and the cabinet team will focus on the rescue operations as well as clarifying the cause of the incident," it said in a statement.