South Korea said Wednesday that its total coronavirus infection cases have exceeded 1,200 as the situation rapidly worsens in the country, with the first case confirmed among U.S. military personnel.

With 284 new cases reported the same day, the number of infections has reached 1,261, and the death toll has risen to 12, up from 10 on Tuesday, according to the Health and Welfare Ministry.

South Korea is on its highest alert over the outbreak of the pneumonia-causing virus, which first emerged in neighboring China, as the number of cases of infection skyrocketed from 51 a week ago.

Most cases have been found in the southeastern city of Daegu and the neighboring county of Cheongdo. In Daegu, there is a cluster linked to a branch of a religious group, while in Cheongdo, there is another linked to a hospital.

Of the 1,261 confirmed cases, 710 were linked to Daegu and 317 to North Gyeongsang Province, which includes Cheongdo, according to a ministry statement.

There is also a rising number of cases in big cities such as Seoul and the southern port city of Busan, prompting concerns about a widening epidemic.