SYDNEY, Dec. 22 (Xinhua) -- An Australian man who drove an SUV into pedestrians in downtown Melbourne on Thursday has mental health problems with a history of drug use and does not have any extremist links, police said on Friday.

The 32-year-old driver, an Australian citizen of Afghan descent, was arrested at the crowded Flinders Street intersection where 19 people were injured in the incident.

The 24-year-old male suspect, who is in hospital guarded by police, made "utterances" to investigators on Thursday night and investigations are ongoing, Victoria state's Acting Police Chief Commissioner Shane Patton said on the ABC News channel.

"We're exploring fully what the motivations for this attack are ... he spoke of dreams and voices ... Now obviously we're continuing to explore this entire incident and trying to ascertain what the motivations are.

"We haven't identified any extremist links with this man. We haven't identified him linked to any groups. We haven't identified anyone inciting him to do any actions," Patton said.

In January, a similar incident involving a 27-year-old man driving his car into pedestrians on nearby Bourke Street at lunchtime claimed six lives and injured at least 30 others. The suspect pleaded not guilty to murder and attempted murder charges earlier this month.

Victoria state's Premier Daniel Andrews said what happened on Thursday was "an act of evil."

"This was an attack on innocent bystanders - people finishing their Christmas shopping, heading home from work, unwinding for the year. They did not deserve this. Our city did not deserve this. Christmas should be a time of celebration, spent with loved ones."