Three Americans were killed Wednesday in a bus crash in the Honduran capital of Tegucigalpa while on their way to the airport to fly back home, the Associated Press (AP) reported. Two of the deceased were students of Columbia University while one was a U.S. healthcare worker.

The deceased were on a volunteer mission to the Central American country and their families were notified of the accident, the New York-based university’s President Lee C. Bollinger said in a statement posted on Facebook. The students were from Barnard College.

“We are in the process of determining the full extent of the injuries sustained by the bus passengers and contacting families of our students. Columbia medical and support personnel are traveling to Honduras overnight to provide additional on-site assistance,” Bollinger said, in the statement.

Isa Alvarado, spokeswoman for the public ministry morgue in Honduras, said those killed — whose identities were not released — were aged between 20 and 45, the AP reported. Twelve more Americans were wounded in the crash and were reportedly in a stable condition. Alvarado added that forensic workers were preparing the bodies to be returned to the U.S.

Firefighters' spokesman Capt. Gustavo Barahona said mechanical failure could be a likely cause for the crash, according to AP.