The stranger fled the scene before any further action could be taken.
The teens had been following a woman and whistling at her prior to the shooting.
The traffic flow was largely unaffected despite the fire.
Before the crime, the victim caught the suspect secretly entering her property to get a drink of water.
Hunger and hot weather are believed to have triggered her symptoms.
The driver tried to flee, but was quickly apprehended.
If convicted, he faces up to three years' jail and/or a fine of up to RM1 million (S$321,000).
All 17 Nepalese arrested so far were found to have overstayed in Singapore after the expiry of their visit passes.
No foul play is suspected, the police said.
A third person was assessed for minor injuries but declined to be sent to the hospital.