Melbourne train network shut down

Melbourne's train network was brought to a halt after a biohazard building alarm forced the evacuation of the Metro control room.

"Train control centre was evacuated due to an (sic) building alarm but staff are now returning. Major delays while we recover from this disruption," Metro Trains tweeted.

Traffic was also affected when boom gates at level crossings across the city became stuck.

Trains are reportedly starting to run again but delays are expected.