A 27-year-old suspect set off smoke bombs in Taipei's main metro station during the Friday evening rush hour before launching into a stabbing rampage, according to authorities.

He killed three people in an attack that spanned the main station, an underground shopping district and another metro stop, while at least 11 others were wounded, according to a revised count from the police on Saturday.

The suspect, who had been wanted for evading military service, died in an apparent suicide after the attack, Taipei's mayor said at briefing on Friday night.

Officials called it a "deliberate act" but said the motive was not immediately clear.

While visiting hospitals on Saturday, Lai offered sympathy and pledged transparency.

"I want to express condolences to those who tragically lost their lives in last night's horrific, violent attack, and to extend my sympathy to their families," Lai said at one of the hospitals.

He added that he has ordered a "full and thorough investigation" and will "give the public a full account of truth."

Violent crime is rare in Taiwan. The last time a similar incident occurred was in 2014, when a man on a stabbing spree in the metro killed four people.