Mexico City  - The rescue of two kidnapped adults in Mexico left five dead - a police officer and four alleged criminals - Tuesday, the authorities said.

Facundo Rosas, who led the operation by the federal police in the state of Mexico adjoining the country's capital, said 20 alleged criminals were arrested alongside the gang's leader, a Mexican citizen with a criminal record in the United States.

The deaths occurred when the suspects resisted the rescue attempt and shot at police.

The kidnappers had held for eight days a 49-year-old woman and her 30-year-old son, Rosas said. The two had been violently abducted from their home.

Rosas explained that the house where the victims were being held was found following an anonymous tip.

In Mexico, an average of three people are kidnapped everyday and are often held for ransom, according to federal authorities.

Thousands of people marched against kidnappings and against violence in general Saturday in several cities across the country. (dpa)