The man suspected of carrying out an attack in Taiwan with a smoke grenade and knife acted alone, police said on Saturday about the incident that killed four, including the attacker.

Chang Wen, 27, from the northern city of Taoyuan, died falling from a building during a police chase on Friday evening in a packed shopping district in central Taipei, police said.

“Based on relevant verification work carried out continuously since yesterday, we have not found that the suspect had any other accomplices,” National Police Agency Director-General Chang Jung-hsin told reporters.

Investigations are ongoing as to the motive, he said.

Premier Cho Jung-tai said late on Friday that the man had been the subject of an arrest warrant, wanted for suspected evasion of Taiwan’s compulsory military service.

Eleven people were injured in the attack, of whom two are in intensive care, the health ministry said.

Chang Wen let off smoke bombs at Taipei’s main train station, then made his way to a mall at a nearby subway station, attacking people both inside the shopping centre and on his way there, police said.

Violent crime in Taiwan is very rare, and in response to the attack, the police presence has been stepped up across the island, including in the bustling capital, Taipei.

“For areas in Taipei city where crowds are expected to gather in various commercial districts, we are upgrading security measures citywide,” Mayor Chiang Wan-an told reporters.

“This includes not only increasing the police presence but also ensuring that all officers are fully equipped with the necessary gear.”

President Lai Ching-te, who visited some of the injured in the hospital on Saturday morning, wrote on his Facebook page that the government would learn the lessons from this incident.

“We will also ensure that rapid-response units can be mobilised immediately when emergencies occur, so as to safeguard public safety,” he said.