MEXICO CITY: A bus carrying a church group plunged into a deep gorge in the southern Mexican state of Chiapas Sunday, killing at least 17 people and injuring 31, authorities said.

The bus fell into a 90-meter (300-foot) gorge in the Motozintla region near the border with Guatemala, according to the local office of the Interior Ministry´s civil protection department.

"At this time, we have registered 17 people who unfortunately lost their lives," the agency said in a statement.

The bus was carrying members of the Seventh-day Adventist Church returning from a retreat in the Pacific coast town of Pijijiapan, local police said.

An apparent mechanical failure caused the accident, according to federal highway police involved in the rescue effort.