Thousands of people arrive in Zocalo Square with the Metropolitan Cathedral in the background, during a protest march in Mexico City May 8, 2011. Thousands of Mexicans on Sunday marched into the capital city to protest the wave of killing that has claimed 38,000 lives since President Felipe Calderon launched his war on drug gangs in late 2006. [Photo/Agencies]

MEXICO CITY - An anti-violence march that began in a central state with a few hundred people and gathered thousands over a four-day trek reached Mexico's capital Sunday, led by a poet whose son was killed by suspected drug traffickers.

People poured into the main Zocalo square in Mexico City, wearing white T-shirts saying "enough bloodshed" and carrying photos of poet Javier Sicilia's slain son.

A few hundred people set off from Cuernavaca in the central state of Morelos on Thursday, marching silently along the 50-mile (80-kilometer) route. Turnout estimates varied widely, but the crowd took up less than half of the main square, which is believed to hold about 100,000 people. It was packed with more than 100,000 in 2008 during another march for peace and justice.

Since then crime attributed to drug trafficking and organized crime has only gotten worse in what one of Sunday's marchers called "la guerra calderonista" _ President Felipe Calderon's war.

In a speech that drew deafening cheers, Sicilia demanded the resignation of Public Safety Secretary Genaro Garcia Luna, lashing out at the government for failing to curb Mexico's relentless drug violence despite the deployment of thousands of soldiers and federal police to cartel strongholds across the country.

"If we have walked and arrived here in silence it's because our pain is so great and so profound, and the horror that causes it so immense, that there are no words to describe it," Sicilia said. "We still believe that it is possible to the country to be reborn and rise from ruin and show the agents of death that the sons and daughters of this country are standing up."

Gruesome violence has surged in the region southwest of Mexico City since drug kingpin Arturo Beltran Leyva died in a December 2009 shootout with marines in Cuernavaca, leading to the splintering of his cartel. Rivals have routinely hung mutilated bodies from bridges along highways connecting Mexico City, Cuernavaca and the Pacific resort city of Acapulco.

Similar turf fighting has claimed more than 34,600 lives nationwide since Calderon deployed federal forces in 2006 to battle cartels.

An unprecedented number of drug bosses have been captured or killed, leading to the splintering of their cartels and fighting that has reached horrific levels, including the discovery last month of secret graves with hundreds of bodies in the northern states of Tamaulipas and Durango.

"Where were the political parties, the mayors, the governors, the federal authorities, the army, the navy, the church, the lawmakers, the businessmen _ where were we all _ when the highways of Tamaulipas turned into death traps for defenseless men and women?" Sicilia said in his speech.

The vast majority of drug-related homicides remain unsolved, provoking widespread anger over the inefficiency of Mexico's overwhelmed and corrupt police.

Among those marching were relatives of Marisela Escobedo, a woman who was killed in northern Chihuahua state while protesting in front of government offices to demand justice for her slain daughter, another case that provoked national furor.

The poet's son, Juan Francisco Sicilia, was killed in Cuernavaca on March 28 along with six other people. Three alleged drug gang members have been arrested in the killings. Investigators say some of those killed may have had a run-in with the suspects days before the attack but that Sicilia was not involved.

Some marchers had T-shirts that read "We are all Juan." Others had signs reading "Marisela Escobedo is here."

Sicilia demanded to know why Calderon "decided to send the army into the streets in an absurd war that has cost us 40,000 lives and left thousands of Mexicans abandoned to fear and uncertainty."

Hours before the marchers reached Mexico City, federal police announced the capture of a suspected drug gang leader in Morelos.

Jose Zarco Cardenas, 22, had recently begun heading operations in Morelos for a gang that broke off from the Beltran Leyva cartel, the Public Safety Department said in statement Sunday. He was arrested in Mexico City on Friday along with an alleged accomplice.