(Updates death toll)
GUATEMALA CITY, Sept 9 (Reuters) - At least 43 people were killed and dozens injured on Monday when a bus went off a cliff on a hairpin bend in rural Guatemala, tumbling some 200 meters (660 feet) into a river at the bottom of a ravine, officials said.
Rescue workers said the bus, which plunged off of a paved highway about 60 km (37 miles) northwest of Guatemala City, was destroyed and more than 40 people were taken to hospitals for treatment.
Investigators do not yet know what caused the crash or what was the final destination of the bus, which was traveling south toward Guatemala City. Rescue workers said conditions were dry and mostly sunny and that the bus was likely over capacity.
"The bus was overloaded," said Sergio Vasquez, a volunteer firefighter at the site.
He said 38 people died at the scene, including six children and 12 women. Five more died at hospitals, he said.
Local television said many passengers were vendors taking farm produce to market.
The government declared three days of national mourning.
The last major bus accident in Guatemala occurred in 2008 when an overcrowded bus slid off a highway and down a 15-meter (50-foot) slope some 65 km (40 miles) southeast of the capital, killing 53. (Reporting by Mike McDonald; Editing by Eric Beech and Bill Trott)