Most of the victims were pilgrims from the southern Mexican state of Chiapas who were on their way back from a trip to Mexico City to pray at the basilica of the Virgin of Guadalupe, the country's patron saint, an official said. Photo AFP

COATZACOALCOS A semi-truck and a bus carrying passengers back from a pilgrimage to a Catholic shrine crashed and burst into flames Wednesday in eastern Mexico, killing at least 21 people, officials said.

Thirty others were injured.

Most of the victims were pilgrims from the southern state of Chiapas who were on their way back from a trip to Mexico City to pray at the basilica of the Virgin of Guadalupe, the country's patron saint, said the head of the Civil Protection service for the state of Veracruz, Guadalupe Osorno.

"The forensics experts at the scene report 17 bodies of passengers who were traveling in the bus, plus two people who died in the semi-truck," she said.

"One person was dead on arrival at the hospital, and another who was in serious condition died."

The Catholic archdiocese of Tuxtla Gutierrez, in Chiapas, sent its condolences to the victims' loved ones in a statement.

"We deeply regret the deaths caused by this accident and share in their families' overwhelming pain," it said.

The accident occurred on a highway in a region known as the Maltrata hills, where the roads wind between peaks that rise more than 2,000 meters (6,500 feet) above sea level.

Emergency officials at the scene said one of the vehicles lost its brakes going downhill and crashed into the other, causing both to erupt in flames and leaving the bus a charred frame lying on its side.

Rescue and forensic workers carried away the bodies after covering them.

In 2006, more than 50 Evangelical Christians were killed in the same region when their bus plunged into a ravine. Authorities said that accident was also caused by faulty brakes. AFP