The fire caused black smoke to billow out from the median of the bridge. Firefighters from Perai brought the fire under control, a spokesman for Penang Fire & Rescue said.

Tenaga Nasional later said the fire involved a 132kV power transmission cable from Bukit Tengah to Bayan Mutiara. The cause of the fire is still under investigation, said TNB chief grid officer Husaini Husin.

He said electricity supply to all consumers in Penang was stable and repairs to the damaged cable would be carried out immediately.

The previous time a similar fire occurred on the bridge was in 1993 when electrical cables under the bridge also caught fire.

Checks on Waze showed the crawl has extended to Perai on the North-South Expressway, with bumper-to-bumper traffic at speeds of 4km/h. Traffic on the Perai bound lane was also at a crawl as most motorists slowed down to gawk.