At least eleven people died and no fewer than 12 were injured in southern Mexico after the bus transporting them flipped over.

Authorities in the state of Oaxaca in a statement said they were still investigating the cause of the accident, which occurred just outside the small town of Santo Domingo Narro.

“I extend my heartfelt condolences to the victims’ families, to whom we will provide the necessary support and assistance during this difficult time,” Oaxaca Governor Salomon Jara said on social media.

The state’s interior minister, Jesus Romero, in an interview on local radio, said the bus was carrying more than 40 people and was en route to the Isthmus of Tehuantepec in Mexico’s south.

According to Romero, it appeared that the passengers were heading home after attending a rally held on Sunday by President Claudia Sheinbaum in the capital Mexico City.