Taiwan’s Premier Cho Jung-tai said the attacks at Taipei Main Station and Zhongshan station were “a deliberate act”, although the motive was not immediately clear.

Cho said in a statement that the suspect wore a mask and threw “five or six gasoline bombs or smoke grenades” at Taipei Main Station.

According to the Taipei City Fire Department, a total of four people were confirmed dead including the suspect, and five others were injured.

The city’s mayor said the suspect had apparently jumped off a building and that one of the victims was killed while trying to stop the attack at the Main Station.

“Unfortunately, he was attacked and passed away… we are all deeply saddened,” Mayor Chiang Wan-an told reporters.

“Currently, we understand the suspect jumped from a building to evade arrest and has been confirmed dead,” he said.

Cho earlier said three people suffered cardiac arrest as a result of the attacks, and several people had “injuries from stab wounds and blunt force trauma to various parts of their bodies”.

Authorities said they were ramping up security across the island in response to the attacks.

“All important locations… including railway stations, highways, subway stations and airports are maintaining a high level of alert and vigilance,” Cho told reporters.

Images released by Taiwan’s Central News Agency show a canister on the ground at the Main Station, with officers examining potential evidence at the scene.

A video posted on social media shows a thick cloud of white smoke covering an underground section of a metro station, with some people standing at a distance.

President Lai Ching-te said Taiwanese authorities will “quickly clarify the details of the case. There will be no leniency and we will do everything in our power to ensure the safety of our citizens.”

Violent crime is rare Taiwan, though an attack in 2014 horrified the normally peaceful island when a man went on a stabbing spree on Taipei’s metro, killing four people. He was executed for the killings in 2016.