Kuala Lumpur Traffic Investigation and Enforcement Department chief Zulkefly Yahya said the urine test of the 40-year-old man returned positive for methamphetamine.

The suspect, who was arrested yesterday, is being investigated under the Road Transport Act for driving under the influence. He is also being remanded under the Danger Drugs Act.

Zulkefly said initial investigations showed the trailer crashed into the steel frame of a pedestrian bridge that was under construction.

This led to the scaffolding and the frame to collapse onto a passing van carrying five people who were on their way to work in USJ 1.

Two women in the van, aged 42 and 47 were killed, while the others – a man and two other women – were seriously injured.

It was reported that the occupants were trapped for a few hours after the incident.

A spokesman for the Kuala Lumpur Fire Department said rescuers had arrived at the scene shortly after receiving an emergency call at 5.58pm.

They were rescued at 9.26pm.