AGUAS BLANCAS, Mexico -- Police armed with semiautomatic weapons unleashed a barrage of gunfire at a group of farmers, killing 18 and wounding 24, survivors say, describing one of the bloodiest clashes between Mexican police and civilians in years.
Versions of how Wednesday's clash began differed. Survivors said they were unarmed and attacked by more than 100 police who surrounded them in what amounted to a calculated massacre.
Police said the farmers, on their way to an anti-government demonstration, had guns and machetes and attacked after being stopped along a road for a routine weapons check.
One police officer's arm was lopped off, authorities said.
Whatever really took place, the public awoke Thursday to grisly TV and newspaper photographs of the carnage that provided a stark reminder of the festering economic, social and political divisions in Mexico.
The clash took place 25 miles from Acapulco in the desperately poor farming state of Guerrero, where crops include marijuana and disputes are often settled with the gun. The state's police have one of the worst human rights reputations in Mexico.
Local farmers said state police deployed along the road hours before the clash, cutting off access to the area.
According to four survivors, scores of police in at least 12 vehicles stopped more than 80 farmers, many of them members of a leftist peasant organization that had been staging anti-government demonstrations.
They said police opened fire into one truck, crammed with dozens of men, women and a child.
When the shooting was over, 18 people were killed, one of them a small girl, and 24 others were wounded, the survivors said.
The survivors said they had no weapons on the old farm truck.