Bomb squad called to Melbourne car park

A shopping centre car park has been shut down in Melbourne, with the police bomb squad called out over concerns about a bus.

A witness has told AAP she and others were escorted from the Northland Shopping Centre and told to turn off their phones about 9pm on Thursday.

Police said the car park was closed as a precaution as officers conducted safety checks on a bus along Murray Road at Preston. The bomb response unit was en route.

Jodie McClelland was one of the shoppers caught up in the scare.

"The security guards were just holding us back and telling one or two of us go at a time," she said.

Outside, she added "there was just police or security guards everywhere searching for something".

The scene was reportedly declared safe before midnight.