SAN MARCOS - A bogus bomb threat forced a daylong closure of San Marcos High School today, four days after a similar criminal hoax prompted heightened security at an elementary school in the northern San Diego-area city.An unidentified person phoned in the threat to the West San Marcos Boulevard secondary school at about 8 a.m. Friday, according to the San Diego County Sheriff's Department."As a precaution, students arriving at school were sent home with their parents,'' Sgt. William Frierson said, adding that administrators put lockdown procedures into effect for those youths and staffers already at the campus.Deputies then combed the grounds and buildings for explosives or any other hazardous materials, aided by bomb-scenting service dogs.``Nothing suspicious was found af
