The injured drivers were found in a conscious state when officers reached at the 21 Woodlands Crossing and they were taken to the Khoo Teck Puat Hospital.
Central Narcotic Bureau Singapore arrested one male and one female suspected drug traffickers from Tampines Street 83 and seized several drugs including a car.
After SCDF was alerted to the accident, paramedics reached the location and diagnosed a victim, whom they pronounced but took rest three to a hospital.
Ex-PM Najib's United Malays National Organisation (UMNO) is believed to have received funds from 1MDB, which is the subject of money laundering probes in at least six countries.
Cash, handbags, watches, jewellery and many more items were seized from official PM house and office, as well as Najib's Kuala Lumpur house and from three units in Pavilion.
Activists say they were disappointed but unsurprised human rights has seemingly disappeared from the agenda as South Korean and American leaders met with Kim Jong Un in recent months.