Time may not be on the side of American journalists Laura Ling and Euna Lee.

The two California-based women, along with their driver, were detained by North Korean border guards this week while filming near the nation’s border with China. They were working on a documentary about refugees for Current TV, a cable network founded by Al Gore. It’s not clear whether the women actually entered North Korea, or whether the border guards snatched them on the Chinese side of the Tumen River.

"We’re working with Chinese government officials in the area to ascertain their whereabouts and welfare," one U.S. official told the Financial Times.

A State Department spokesman said Friday, "The facts are not quite clear," and the U.S. is trying to get all the details — including confirmation from North Korea — that Ling and Lee are, in fact, in custody. U.S. officials are working with the Chinese government, North Korea’s mission to the United Nations and the Swedish Embassy that represents the U.S. in Pyongyang.

"Right now, what’s – the priority for us is trying to find out exactly what happened and go from there," said the spokesman. The Committee to Protect Journalists has called on diplomats in China, North Korea and the U.S. to cooperate to ensure the safe release of the journalists and their guide.

Negotiators trying to free Chinese American Ling and Korean American Lee may have to work fast to get them out before North Korea tests its long-range missile April 9. Tensions are already high over that. "It’s as though Pyongyang timed the episode of the journalists deliberately to heighten a sense of calamity and grab the attention of a world grown weary of mere rhetoric," the Asia Times says.

Ling is the sister of Lisa Ling, a former co-host of ABC’s "The View" who currently works as a correspondent for National Geographic Channel’s "Explorer" show. The Lings’ father said he spoke to his missing daughter two days before news of her detention broke. "I said, ‘Be careful. Have a safe trip.’"