GUATEMALA CITY (AP) _ Four armed men kidnapped a U.S. woman and her two young children as she dropped them off at school, and a man later called demanding $20,000, police said Wednesday.

Sheryl Swingle de Gomez, 42, her daughter Clementina, 6, and her son Juan Pablo, 4, were abducted Tuesday morning in San Lucas Sacatepequez, 15 miles northwest of the capital.

Witnesses said the kidnappers forced them into a van and drove away.

``A man telephoned the family and told them if they wanted to see the woman and children safe and sound they had to pay a $20,000 ransom,'' said police spokesman Gonzalo Figueroa. He did not say when the call came.

Mrs. Swingle de Gomez is a longtime resident of Guatemala. The family did not contact the U.S. Embassy, said spokesman John Roney. He said U.S. officials would ``cooperate with local authorities upon request.''

Police say an average of six kidnappings are reported in Guatemala each week, and last year people paid more than $36 million in ransom.

Last month, three people were jailed for 10-15 years for their involvement in the 1994 kidnapping of Georgina Lira Robbins, the 6-year-old daughter of Henry Robbins Cohen, an American businessman who lives in Guatemala.

Last week Congress approved a controversial law making all kidnappers eligible for the death penalty. A police squad formed a month ago is being trained by former FBI agents to combat kidnapping.