THE Bomb Squad and Hazmat were deployed to an electricity substation in Penrith following the discovery of a device with what looked like a detonator attached to it this morning.

Workers at the Kingswood electricity substation on Smith St found what was understood to be a petrol bomb with a detonator shortly after 8am.

media_camera Investigators return from examining the device. Picture: Peter Kelly

Police, fire crews and bomb technicians attended and set up an exclusion zone as they investigated the device.

The device was said to be a lunch box sized container full of a petrol-looking substance and a device similar to a mobile phone attached with wires protruding, but police only later described the items as a number of “unattended objects”.

After hours of investigation with the area blocked off, NSW Police said the device was not an explosive.

“An initial examination was not able to determine the contents of the objects, however no explosives were detected,” NSW Police said in a statement.

“Police have apologised for any inconvenience and have thanked residents and motorists for their understanding.”

media_camera A Fire and Rescue officer walks away with an object from the scene. Picture: Peter Kelly

The device was removed from the site and will be forensically examined, with police saying they were unable to determine what the object was and confirming it would be subjected to forensic testing.

“The examination has not been able to determine the contents [of the device],” police said.

“They will be removed and forensically examined.”

media_camera Police rescue and other emergency services near the bomb. Picture: Peter Kelly

media_camera The bomb has been described as being lunch box sized. Picture: Peter Kelly

A source said the device had been placed strategically — the substation controls power to the electricity grid feeding the general Penrith area.

This includes its nearby hospitals.

Streets have been reopened to traffic.