A State Department spokeswoman said Thursday that officials are still working to learn what it can about reports that a Malaysian passenger aircraft was shot down over Ukraine by pro-Russia separatists, including whether any U.S. citizens were aboard that flight.

“At this point we do not have any confirmed information about casualties, the cause or additional details,” State Spokeswoman Jen Psaki told reporters.

In this photo taken with a mobile phone provided by Andrei Kashtanov, smoke rises from where a Malaysia Airlines commercial plane crashed in eastern Ukraine, Thursday, July 17, 2014. Malaysia Airlines has said 295 people were aboard the flight from Amsterdam to Kuala Lumpur. (AP Photo/Andrei Kashtanov)

“We’re closely monitoring the situation. The secretary is of course aware of these reports, and we’re seeking additional information.”

According to press reports, the flight’s manifest listed 23 passengers on the flight with American citizenship. But Psaki said State was still working to confirm that information.

“We’ve seen the public reports,” she said. “We don’t have any additional details at this point on American citizens. We’re looking to, of course, obtain that information.”

According to Ukrainian officials, all 295 passengers on the plane are believed to be dead. The U.S. Federal Aviation Administration in April prohibited some flight operations in the area because of potential danger due to the disputed airspace between Ukraine and Russia.