South Korea ? Two American journalists were missing today after they reportedly were detained by North Korea for ignoring warnings to stop shooting footage of the reclusive country.

Journalists Laura Ling and Euna Lee, reporters for former Vice President Al Gore’s online media outlet Current TV, were seized Tuesday along the Chinese-North Korean border, according to news reports and an activist who had worked with them. Their Chinese guide also was detained, although a third journalist with the group, Mitch Koss, apparently eluded capture.

U.S. officials expressed concern to North Korean officials about the reported detentions and said they were working with the Chinese government to ascertain the whereabouts of the Americans.

“When you have two American citizens who are being held against their will, we want to find out all the facts and gain their release,” State Department spokesman Robert A. Wood said Thursday in Washington.