Rio De genrio: Early on Thursday (local time), a passenger bus carrying mostly foreigners crashed into a ravine in western Mexico, killing at least 18 people, according to state officials. Some of the victims were en route to the US border.

The bus had been carrying about 42 passengers, including people from the Dominican Republic, India, and African countries, on its way to the northern border town of Tijuana.

According to a statement from the state of Nayarit, the bus driver was detained after police noticed him speeding around a bend in the road.

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According to officials, efforts are still being made to identify those who passed away on Thursday afternoon.

A woman's condition was described as "delicate" and 20 people were taken to the hospital to treat their wounds, according to the state government.

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Officials reported that the bus, which was a part of the Elite passenger line, crashed on the highway outside of Tepic's state capital near Barranca Blanca.

According to Jorge Benito Rodriguez, secretary of security and civil protection for Nayarit, rescue efforts have been "extremely difficult" because the ravine is 40 metres (131 feet) deep.

Requests for comment from the bus company and Mexico's migration institute were not immediately fulfilled.

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In February, a bus carrying migrants from South and Central America crashed in central Mexico, killing 17, and last month, a bus crash in the southern state of Oaxaca left 29 people dead.