LATEST at 3pm: Police said a 54-year-old man was arrested on suspicion of making threats to kill and is still in custody.
Officers stopped his vehicle this morning as part of a search for a man "in connection with a domestic-related incident".
The package was declared safe by Royal Navy bomb disposal squad experts. Members of the public are being allowed through the police cordon on foot although vehicles are not being let through at this time.
A police spokesman said: “This was an isolated incident and no-one else is sought in connection with it. The safety of the public remains paramount in any incident such as this and at no time were they at any risk.
"We would like to thank the public for their patience this morning.”
A massive emergency operation launched in Truro this morning is thought to have been sparked by bottles containing unknown liquids in a homeless man’s car.
The emergency response, involving the police, a Royal Navy bomb squad and the fire service, saw the Truro Business Park closed down and dozens of workers left stranded.
Emergency services swooped into the Threemilestone area this morning and arrested a 54-year-old man.
Police went into Truro Business Park at 6.30am and reported the discovery of a “suspicious package in a vehicle”.
A section of the business park was closed off and experts from the Royal Navy bomb disposal squad in Plymouth rushed to the scene.
Photographs taken by Threemilestone resident Chris Whiteleg show the bomb disposal squad’s robotic device removing objects from a silver Skoda parked on the road.
Mr Whiteleg told the West Briton he had spoken with a man in his fifties who had been sleeping in the Skoda over the past three months.
He said: “He said he had split up from his wife and he was living in his car.”
The pictures show several plastic bottles in the boot of the Skoda containing liquids.
The roads into the business park were closed but no cordon was in place at the lower end of the park.
Mr Whiteleg, who was out walking his dog, said: “I saw this man’s car being picked apart by the bomb squad drone.
“The drone was going around the car opening doors and emptying stuff out.
“I had spoken to the guy before, he seemed fine to me.”
Police confirmed the arrested man was from Cornwall and was in custody at Camborne Police station. They declined to comment on the reasons for the man’s arrest.
To see coverage of events as they unfolded this morning click here