Four bodies were found Wednesday east of the border city of Matamaros, near where three young Americans vanished more than two weeks ago, a Mexican state official said.

Tamaulipas state investigator Raul Galindo Vira would only confirm that four bodies had been recovered and declined to discuss who they might be.

A second state official said investigators were trying to determine if the dead include three siblings from Progreso, Texas, who disappeared with a fourth person Oct. 13. The official, who said the bodies were badly decomposed, insisted on speaking anonymously because he was not authorized to speak to the press.

Mexican authorities on Wednesday asked the siblings' father what they were wearing when they disappeared, mother Raquel Alvarado told The Associated Press.

Alvarado said witnesses saw armed men take her daughter, Erica Alvarado Rivera, 26, and her sons, Alex, 22, and Jose Angel, 21, in El Control, a small town near the Texas border west of Matamoros. The three were visiting their father in Mexico.

According to Alvarado, her daughter, Erica, mother of four children aged 3-9, drove her black Jeep Cherokee across the border Oct. 12 and dropped it at her father's house in El Control. She visited her boyfriend there and the next morning called her brothers to ask them to bring the Cherokee to a roadside restaurant where the couple was eating. The three siblings planned to return to Progreso together from there.

When Alex and Jose Angel Alvarado arrived to pick up their sister, they saw men "pushing their sister and her boyfriend and hitting her," Raquel Alvarado said. The brothers tried to intervene, witnesses said, but were taken away with their sister and her boyfriend. Witnesses said the armed men identified themselves as Grupo Hercules, a police security unit for Matamoros city officials, and were traveling in military style trucks. She said witnesses also saw federal highway police, "but no one did anything."

The Matamoros mayor's office and a spokeswoman for the city did not respond to requests for comment.

As night fell Wednesday, Martha Hernandez, who raised 32-year-old Jose Guadalupe Castaneda Benitez, Erica Alvarado's boyfriend, since he was 3, waited outside state police offices in Matamoros for any word on his whereabouts. She said no one had told her until she arrived that four bodies had been found.

Hernandez said a friend who saw Castaneda and the Alvarados being picked up also told her the Hercules unit was responsible, and she expressed anger at the Matamoros mayor.

"We will keep searching," she said. "They can't just disappear. We are going to be like in Guerrero."

Hernandez was referring to the southern state of Guerrero, where the disappearance of 43 teachers college students Sept. 26 at the hands of police has touched off a national controversy in Mexico. Demonstrators demanding authorities do more have marched in Guerrero as well as Mexico City and Acapulco, and protests have sometimes turned violent, as happened Wednesday in Guerrero's capital, Chilpancingo.

Authorities say police in the Guerrero city of Iguala attacked the students on orders from the mayor because of fears the students planned to disrupt a speech by the mayor's wife. Officers allegedly turned the students over to the Guerreros Unidos drug cartel. In a month of searching the area, including combing a ravine outside a nearby town on Wednesday, federal authorities have discovered several clandestine mass graves but no sign of the students.

President Enrique Pena Nieto held a closed-door meeting Wednesday with parents of the missing students.