Mexico City ? Hundreds of thousands of frustrated Mexicans, many carrying pictures of kidnapped loved ones, marched across the country Saturday to demand government action against a relentless tide of killings, abductions and shootouts.

The mass candlelight protests were a challenge to the government of President Felipe Calderon, who has made fighting crime a priority and deployed more than 25,000 soldiers and federal police to wrest territory from powerful drug cartels.

Cries of “enough” and “long live Mexico” rose up from sea of white-clad demonstrators filling Mexico City’s enormous Zocalo square. The protesters held candles twinkling in the darkness as they sang the national anthem before dispersing.

“I’ve had enough. Kidnapping, corrupt police, a rotten judicial system,” said Ricardo Robledo, a 43-year-old music producer who said he had been robbed numerous times. “This may begin a change.”

City officials refused to give a crowd estimate, but the Zocalo can hold nearly 100,000 people. Tens of thousands overflowed into the surrounding streets, unable to squeeze into the square. Thousands more protested in cities across the country.

Despite the arrest of several drug kingpins, little has improved since the Calderon government began its crackdown.

Homicides have surged as drug cartels battle one another for control of trafficking routes and stage vicious attacks against police nearly each day. In the gang-plagued border state of Chihuahua alone, there have been more than 800 killings this year, double the number during the same period last year.