SAN FRANCISCO (Reuters) - Police in northern California are investigating the origins of a bomb that was concealed inside a newspaper and exploded when a man picked it up off his driveway on Sunday morning.
The man, who was not identified, was taken by ambulance to a hospital with unspecified injuries he suffered in the blast, according to a statement posted online by police in the town of Vacaville, about midway between San Francisco and Sacramento.
The man's injuries were described as "non-fatal," but the blast touched off a security scare that lasted several hours.
Police said they ordered the evacuation of 40 to 50 nearby homes as a precaution as investigators were called in from the Travis Air Force Base bomb squad, the FBI, the federal Bureau of Alcohol, Tobacco and Firearms and the California Highway Patrol.
Teams with bomb-sniffing dogs and bomb-detection equipment searched the immediate vicinity for more explosives, but none were found, police said. Calls from residents elsewhere in the city worried about suspicious packages also turned up nothing.
Most residents were allowed to return to their homes by 4 p.m. local time, about five hours after the bomb exploded.
Police said the bomb appeared for now to be an isolated incident, but it remained unclear whether the man injured was singled out for the attack or was a random victim.
(Reporting by Gabrielle Saveri in San Francisco; Writing by Steve Gorman; Editing by Peter Bohan)