Bearing white balloons and fake bloodstains, tens of thousands of demonstrators crowded Mexico City's historic downtown Sunday to call for an end to the country's unrelenting drug violence.

The primary target of the protest was President Felipe Calderon, who has ruled during a period of extraordinary bloodshed. More than 34,000 people have been killed since Calderon declared an all-out assault on drug cartels after taking office four and a half years ago.

Demonstrators, holding placards saying "No more blood!" and "We're fed up!", urged the conservative Calderon to drop his military-led strategy.

"Mexicans can't take more of this fear. This country is overwhelmed by violence as never before," said Maricarmen Luna, a 36-year-old teacher, as she marched toward the main plaza, or Zocalo.

Mexican media cited Mexico City police estimates of 90,000 in the plaza, though organizers put the number at more than double that.

The gathering was led by poet Javier Sicilia, whose 24-year-old son and six other people were seized and slain by gunmen in Cuernavaca in March. Since then, the elder Sicilia has been a frequent presence on Mexican television, criticizing Mexican leaders across party lines and labeling the drug war a failure.

Sicilia drew applause when he called for the resignation of Mexico's public safety secretary, Genaro Garcia Luna.

"No more deaths! No more hatred!" Sicilia said.

Although protests are frequent in the clamorous capital, this demonstration has dominated headlines. Mexican media tracked Sicilia and a core group of several hundred marchers who set out Thursday from the city of Cuernavaca, about 60 miles south.

By Sunday, the gathering had grown into a happening, with room for just about anyone who had a strong opinion. Along with left-leaning political activists, the crowd included peace-minded school groups, disgruntled electrical workers, advocates of women's rights, critics of neo-liberal economics, drum groups and hula-hoop dancers.

Many banners decried corruption and impunity, two of the country's most oft-cited problems. One youngster held a sign slamming "mediocre teachers." A day earlier, youths went around dumping red paint in fountains in and around downtown to symbolize the bloodshed.

Calderon is under mounting pressure as the carnage rises across Mexico. But the conservative president has said it would be irresponsible for his government to withdraw from the battle against Mexico's powerful and violent drug-trafficking organizations.

Most of the killing has resulted from fighting between rival groups, but numerous bystanders have also died in the crossfire. In addition, the military has been frequently charged with human rights abuses.

Organizers presented a manifesto calling for political reforms and changes in the crime strategy to improve the safety of ordinary Mexicans while attacking graft and impunity that allows wrongdoers to avoid punishment. Demonstrators urged the United States to stem the southbound flow of weaponry that helps arm the drug cartels.

Coordinated demonstrations were held in Washington and across Europe.

Martin Martinez, 44, a chemist, said the crisis underscored the bankruptcy of all the country's political parties. He held a sign saying, "We've had it up to here."

"It's against violence," Martinez said of the Mexico City protest, "but beyond that is a vision for real change."

Mexicans have taken to the streets before in large numbers to protest crime and insecurity, only to watch the violence rage on. But some of those taking part Sunday said the killing had reached an intolerable level.

"We know there will be more — more blood, more death. But how far does it go?" asked Yazmin Galicia, 27, a biologist, who had painted "no more blood" on her right cheek.

"This is a little grain of sand in all that we have to do."

ken.ellingwood@latimes.com

Cecilia Sanchez of the Times' Mexico City Bureau contributed to this report.