A popular American English teacher was taken from his school in Yemen's capital, Sana'a, on Tuesday by gunmen wearing civilian clothes, students said.
Peter Willems is principal of the Exceed Language Center.
Students say gunmen surrounded the school while others burst into the building and took Willems to an undisclosed location.
Reports say the gunmen are Houthi rebels, who control the capital.
No one has claimed responsibility, and it is unclear if Willens was arrested or kidnapped.
Some of the students are reported to be in a panic.
Yemeni-based journalist Hakim Almasmari tweeted that Willems has been teaching English in Yemen since 2004 and is "loved by thousands."