MEXICO CITY, Dec. 30 (Xinhua) -- At least eight people were killed and 48 others injured when a bus fell into a ravine Sunday in Mexico's central Guanajuato state.

The accident took place in Lecon, city authorities said in a statement.

"Unfortunately, there are eight fatal victims so far, including the driver," they said.

Manufactured in 2015, the bus has undergone the latest mechanical check-up, according to the city's transit bureau.

Some of the injured are in serious condition, Daniel Diaz, the state secretary of public health, told reporters.

Among those seriously injured were a pregnant woman and her 35-week-old baby, said Diaz.

Investigation was underway to determine the cause of the crash.