(CNN) -- Law enforcement officials in southern California searched urgently Wednesday for a 3-year-old boy who was kidnapped at gunpoint during a weekend home invasion.



Briant Rodriguez, 3, was taken by armed men during a home invasion in San Bernardino, Caifornia, police say.



Two men broke into a house in the San Bernardino area on Sunday and tied up the boy, Briant Rodriguez, his mother and other siblings.



They ransacked the house and fled with the boy, authorities said.



One of the children freed himself and untied the rest of the family, CNN affiliate KTLA reported. The boy's father was at work at the time, KTLA said.



An Amber Alert was issued late Sunday. Sheriff's deputies in San Bernardino County released composite sketches of the suspects during a news conference on Tuesday.  Watch how the boy was taken at gunpoint »



Sheriff's officials said they placed the boy's picture on billboards along the U.S.-Mexican border and have followed up on half of 80 or so leads from the Amber Alert tip-line.



Federal, state and local authorities are working the investigation, which is sparing no expense, Sgt. Doug Hubbard. said. "Every type of known technology is working on this case," he added.



Officials said the kidnappers have not contacted authorities or the parents.



At the news conference, the boy's mother, Maria Millan, held her son's T-shirt and begged that he be released.



"My son, my son, my pretty son," she said. Millan said she told the kidnappers "I don't owe you a thing" and has said she didn't know the men.



There has been speculation that the boy's abduction was a case of mistaken identity or carried out by people involved with organized crime. Authorities say they have found no motive in the case, and they are not ruling out any possibility. They said the parents are not suspects.



Hubbard, the sheriff's department's lead investigator in the case, said "the family obviously has been very distraught."



"Every second that goes by for us is critical," Hubbard said of the round-the-clock and robust investigation. He also added that in his 20-year career he has never experienced a case where a home-invasion robbery resulted in a kidnapping.



Briant is described in the Amber Alert as a Hispanic male who was last seen wearing a yellow shirt with blue sleeves and blue-striped shorts with two different colors of blue. The boy's hair is longer than shoulder length.



Both suspected kidnappers are Hispanic males -- one 5-feet, 5 inches tall, between the ages of 18 and 20 with a thin build, unknown hair and eye color, last seen wearing a black baseball hat, blue jeans and green T-shirt. The other is 5-foot-10, around age 24 with a thin build, black boots, a black shirt and a bandanna.
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question: Where did the home invasion take place?, answer: San Bernardino, Caifornia, | question: Who posted billboards  along U.S.-Mexico border?, answer: Sheriff's deputies in San Bernardino | question: Where were billboards placed?, answer: along the U.S.-Mexican border | question: Who was taken during home invasion?, answer: Briant Rodriguez, 3, | question: When was the boy taken?, answer: during a home invasion in San Bernardino, | question: When was Briant Rodriguez taken from his home?, answer: Sunday | question: What haven't abductors tried to do?, answer: have not contacted authorities or the parents. | question: What the police said?, answer: Briant Rodriguez, 3, was taken by armed men during a home invasion in San Bernardino, Caifornia,