So what do i do now?

First is to always be quick to react when you see anyone breaking the law. Call the authority and make you you're safety is the priority concern and leave the issue to the authorities to handle. Keep updating the authorities of what is going on and keep at a distance.

For car parks, perhaps the authorities could install security cameras in and around the car park so that we can catch these criminals in action and to send out words that car parks are safe and secure. Or if anyone witnessed the crime, they could call up the police and report what they saw.

For wanted criminals or dangerous suspects, always remember to keep yourself out of harm's way before making the call to the police as you might end up in trouble and escalating the situation even more. Update the police of how he looks like and what he is wearing. Police could always keep the public on the lookout by placing posters shown below to further increase awareness,

Emergency calls
Singapore police force - 999
Singapore civil defense force - 995

Hotlines
Police - 1800 2550000
Internal security department counter terrorism centre - 1800 2626473