The US State Department's electronic system for checking every visa applicant for terrorist or criminal history failed worldwide for several hours late Tuesday because of a computer virus, leaving the US government briefly unable to issue visas. The virus crippled the department's Consular Lookout and Support System, known as CLASS, which contains more than 12.8 million records from the FBI, the State Department and US immigration, drug-enforcement and intelligence agencies. Among the names are those of at least 78,000 suspected terrorists. In an internal message sent late Tuesday to embassies and consular offices worldwide, officials cautioned that "CLASS is down due to a virus found in the system." There was no backup system immediately available, and officials said they could not predict how long the outage might last. Within hours, the system was back up and running. A spokeswoman for the US embassy in Seoul, Maureen Cormack, said it was a "short outage" and "not a major problem." She said interviews for visa applicants continued but any decisions could not be made until the system was back up.