The company said the Boungou mine site remains secure, but operations have been suspended out of respect to the victims and those impacted.
"The convoy, escorted by military personnel, comprised five buses transporting SEMAFO national employees, contractors and suppliers", the company said in its statement.
The company said those numbers were yet to be officially confirmed. In August 2018, a Semafo employee and a subcontractor were killed when a bus carrying workers was attacked, and five police officers and an employee were killed in another attack a few days earlier. But two security sources said dozens may still be unaccounted for.
Semafo tightened security at its mine past year following attacks that killed three workers and five security officials.
The ambush represents one of the deadliest attacks in a recent spate of violence in the historically-calm landlocked nation, which has been infiltrated by jihadists, active for years in neighbouring Mali.
The United Nations' secretary general Antonio Guterres condemned the deadliest attack in almost five years of jihadist violence in the country and expressed his condolences to the families of the deceased, as well as to the people and government.
Reports indicate that hundreds of people have been killed so far this year and more than 150,000 have fled their homes due to attacks across the Sahel region.
The country's badly equipped, poorly trained and underfunded security forces have been unable to stem the violence, which has intensified throughout 2019 to become nearly daily.
Dozens of people were feared still missing on Thursday.
Wednesday's attack happened in eastern Burkina Faso, about 25 miles (40 km) from the Boungou mine, which is owned Canada's Semafo company.
Semafo was quick to release a statement saying that the mine "remains safe and our operations have not been affected", but the movement in SMF stock today clearly shows that investors are anxious about the future of operations in Burkina Faso.