Three volunteers with a U.S.-based aid organization were killed and 30 others injured Wednesday when their bus flipped over on a highway in southern Honduras.

Olivia Varley Erhardt, 20, and Abigail Flanager, 45, succumbed to their injuries while being treated at the Adventist hospital in Valle de Angeles, near Tegucigalpa, hospital chief Reinaldo Canales told reporters.

A third woman, 21-year-old Daniela Moffsson, died at a hospital in Tegucigalpa, according to an official bulletin.

The accident took place on the road from Valle de Angeles to the capital, fire rescue spokesman Capt. Gustavo Barahona said.

The volunteers were working in Honduras under the auspices of the non-profit organization Global Brigades.

The aid workers were on their way to Tegucigalpa for their return flights to the United States, Barahona said.