MEXICO CITY (Reuters) – Members of Mexico’s National Guard are suspected of killing two civilians this weekend in the northern border city of Nuevo Laredo, including a pregnant teenager, a state official and local media said on Monday.

The shooting was likely due to a mix-up because a vehicle with gunmen in it had been reported in the area, the official said, speaking on condition of anonymity because the case is in federal hands. Survivors of the shooting identified National Guard members as their attackers, the official said.

A spokesperson for Tamaulipas state prosecutors said the investigation was with the federal attorney general’s office, which did not respond to a request for comment.

The National Guard did not respond to a request for comment.

Newspaper El Universal reported a 15-year-old girl, who was eight months pregnant, and a 54-year-old man died of their injuries after suspected National Guard members opened fire on the vehicle they were traveling in on Sunday.

Doctors performed an emergency caesarian to try to save the unborn child’s life, but it died, newspaper La Jornada said.

At least three other people in the vehicle were injured, according to media reports. News network Milenio said the vehicle had license plates from the U.S. state of Texas.

The incident comes amid criticism from civil society organizations about the militarization of public security.

The Nuevo Laredo Human Rights Committee said one of the people injured in Sunday’s shooting, Luis Rodriguez, told it that the National Guard was responsible.

The committee said Rodriguez reported he had set out with friends including the pregnant teenager, identified as Miriam Flores, in an SUV with Texas license plates.

A person familiar with the investigation said by the time police were informed of the shooting, the National Guard and emergency services were at the scene.

Nuevo Laredo and the surrounding state of Tamaulipas has long been plagued by gang violence.

City mayor Carmen Lilia Canturosas on Facebook offered condolences to the victims, without specifying what was behind the incident. Authorities were investigating, she said.

(Reporting by Dave Graham; Additional reporting by Daina Beth Solomon, Lizbeth Diaz and Kylie Madry; Editing by Christopher Cushing)