At least 21 people died in three separate incidents of organized crime at the weekend in Mexico, with the most gruesome attack, by hired hitmen, occurring in the southern Guerrero state.

About 60 gunmen stormed a ranch in Guerrero Sunday, killing 10 people and leaving another six wounded, authorities said, after the second such incident in two days.

The attack with automatic weapons took place in Petatlan, on the property of a prominent rancher.

"Early this morning (Sunday), shortly after midnight, some 60 gunmen launched an assault on the home of Rogaciano Alba Alvarez, head of the Guerrero Cattlemen's Association, with at least nine people killed and another six seriously injured," a state official told AFP.

Another person died later on the way to the hospital. Alba Alvarez was not among those killed.

Hitmen arrived at the Alba ranch in six pickup trucks and opened fire with AK-47s, killing the ranch workers before "they apparently also kidnapped one of his daughters," the official added.

The violence came just 24 hours after Alba narrowly escaped an attack by another hit squad Saturday at a hotel in Iguala, also in Guerrero state. Seven people were killed in that incident and another eight wounded.

The hotel was hit as the ranchers were preparing an industry convention.

Alba, who also was targeted in an attack in 2006, is a past mayor of Petatlan (1993-1995). Local media have linked him to paramilitary groups accused of killing 17 members of a local rural workers organization.

Meanwhile, four police officers were killed in an ambush in the northern state of Sinaloa late Friday, authorities said. A local media report said another two local police officers had also been killed.

Federal and state authorities on Friday arrested 13 hitmen in Sinaloa and seized weapons and 379,000 dollars as part of the government's national anti-organized crime operation.

Since December 2006, President Felipe Calderon's federal government has deployed 36,000 military troops and thousands of police around the country in an operation aimed at clamping down on organized crime.

Officials claimed the rising death toll showed that criminals were panicking about the clampdown.

"This reaction by organized crime reflects how the Mexican government is fighting it in an unprecedented and systematic way," Public Safety chief Genaro Garcia Luna said at a weekend ceremony honoring policemen slain in recent days.

So far, organized crime has been behind a total of 1,100 deaths throughout Mexico since the beginning of this year, according to a tally by El Universal newspaper.