A trailer rammed eight workers undertaking highway maintenance on the North-South Expressway near Gopeng this morning, killing four of the workers and injuring the other four, police said.

Perak Chief Police Officer Datuk Mohamad Shukri Dahalan said the accident happened at about 4.30 am at Km294.1 of the highway as the lorry went out of control while going down an incline during a drizzle.

Before mowing down the Propel (Projek Penyelenggaraan Lebuhraya Berhad) employees, the lorry crashed into four vehicles, used by the Propel workers parked on the emergency lane, he said.

Mohamad Shukri said the trailer driver and the attendant were also injured in the accident.

He identified the dead Propel workers as Ismady Mohd Rodzi, 32, of Kulim, Kedah; Shaharuddin Abd Aziz, 51, of Kuala Kangsar, Perak; Mohd Shafie Ismail, 56, of Taman Shatin, Ipoh; and Hafiz Yunus, 39, of Kuala Lumpur.

The injured Propel workers were Dino Azmi, 36, Azhan Ismail, 44, Mahyuddin Idris, 48, and Shafudin Abdul Jalil, 31, while the lorry driver was identified only as Zulkifli and the attendant as Mohd Rozi Mat Sharif, 44, he said.

Mohamad Shukri said the bodies were sent to the Raja Permaisuri Bainun Hospital (HRPB) and the injured to the HRPB and the Kampar Hospital.

"The trailer lorry, travelling from Johor Baru to Ipoh, rammed into the eight Propel workers who were undertaking maintenance work on the left lane of the highway," he told a news conference here.

Three of the workers died on the spot and the fourth died at the HRPB, he added.

Mohamad Shukri said the lorry driver would be detained for investigation after he had undergone treatment.