Airlifted to hospital: The severely injured man from Vacaville, California, is removed from the blast scene by paramedics after the pipe bomb exploded
An elderly man has been severely injured after a pipe bomb hidden inside a Sunday newspaper - and maliciously left on his doorstep - exploded when he picked it up.
The wounded man - who lives in Vacaville, halfway between San Francisco and Sacramento - was airlifted to hospital and residents of a dozen neighbouring homes in the 900 block of Cashel Circle were evacuated as bomb squad experts searched for other devices.
The man's details and the nature of his injuries have not yet been released.
Vacaville police spokesman Mark Mazzaferro said the incident was being investigated by officers from Vacaville police, Solano County Sheriff's Department, the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives and Travis Air Force Base bomb squad.
It was not yet known whether the victim was the target of the pipe bomb, or whether it was a potentially deadly prank.
Mr Mazzaferro denied early reports that at least one other device found in the neighbourhood. He said USAF sniffer dogs had been deployed in the area.
Evacuated residents were being housed at the local community center while the investigation continued.
Residents spoke of their fear at their otherwise quiet neighbourhood being targeted in such an attack.
Resident David Wheeler told News 10: 'It's a little scary. It makes you want to have some type of home security to check to see who is stopping by your home at night.
Police confirmed that the bomb exploded around 10am. It was not yet known whether it was set off by being picked up or whether it was remotely detonated