Veracruz, Mexico ? A vastly overcrowded passenger bus veered off a highway emergency ramp and crashed through a metal barrier Monday, plunging more than 650 feet into a ravine in eastern Mexico. At least 67 people were killed, including four children.

Four people – including an 8-year-old girl – were injured in the wreck that came as the bus traveled on steep mountainous roads. The bus had already traveled for more than 10 hours as it returned from an Easter week gathering in the western city of Guadalajara to the passengers’ home state of Tabasco, on the Gulf Coast.

Rescuers ended their search for victims after recovering 63 bodies, said Rosa Elvira Gonzalez of the State Attorney General’s Office. She said four passengers died at local hospitals.

The bus, equipped to hold 46 seated passengers, was carrying 71, some of whom were standing, said Federal Preventive Police Cmdr. Reinaldo Ascencio Cavazos. He said the owner of the bus was detained for questioning. Ascencio said the passengers belonged to two religious groups, although there was some confusion as to their identities.

Police did not immediately know what caused the crash, but said the driver had been trying to maneuver into a lane designed for vehicles that have brake or other mechanical failure as the bus descended one of the area’s many winding roads. The bus fell between 650 and 820 feet before coming to rest at the bottom of a ravine, authorities said.

Federal Preventive Police official Arturo Corona told W Radio the bus was traveling around 70 mph. Buses often are required to limit their speed to 60 mph.

Hundreds of thousands of Mexicans filled the highways Sunday and Monday as they returned from Easter week vacations. The holiday typically sees a large number of highway deaths. The highway where the bus was traveling is considered to be one of the 15 most dangerous in the country, Corona said.