Sydney light rail service is suspended: L2 and L3 trams impacted

Light rail services in Sydney's CBD have come to an abrupt halt, sparking widespread commuter chaos ahead of the busy afternoon travel period.

Overhead electricity wires fell onto a tram at Rawson Place in Haymarket shortly before 11am on Tuesday morning.

L2 and L3 services are currently not running between Central and Circular Quay or out to Randwick and Juniors Kingsford L2 services on the Dulwich Hill line have also been disrupted.

Buses on routes 438X, 440 and 461X buses have also been diverted.

Commuters travelling between Central and Circular Quay are urged to catch a train.

Authorities are still scrambling to work out what caused the wires to come down after a morning of chaos on Sydney's roads.

'Crews are on-site at the moment, and we're hoping to have [services] back up and running before the PM peak,' a Transport for NSW spokesperson said. 

Hours earlier, Sydney's roads were plunged into chaos after routine test of fire sprinklers in the M8 tunnel caused traffic mayhem, including a 26-kilometre jam on the M5.