Mexico’s National Guard fatally shot two Colombians and wounded four others in what the Defense Department claimed was a confrontation near the U.S. border.

Colombia’s foreign ministry said in a statement Sunday that all of the victims were migrants who had been “caught in the crossfire.” It identified the dead as a 20-year-old man and a 37-year-old woman, and gave the number of Colombians wounded as five, not four. There was no immediate explanation for the discrepancy. The victims were identified by the foreign ministry as Yuli Vanessa Herrera Marulanda and Ronaldo Andrés Quintero Peñuelas.

Mexico’s Defense Department, which controls the National Guard, did not respond to requests for comment Monday on whether the victims were migrants, but it said one Colombian who was not injured in the shootings was turned over to immigration officials, suggesting they were.

If they were migrants, it would mark the second time in just over a month that military forces in Mexico have opened fire on and killed migrants.

On Oct. 1, the day President Claudia Sheinbaum took office, soldiers opened fire on a truck, killing six migrants in the southern state of Chiapas. An 11-year-old girl from Egypt, her 18-year-old sister and a 17-year-old boy from El Salvador died in that shooting, along with people from Peru and Honduras.

The most recent shootings happened Saturday on a dirt road near Tecate, east of Otay Mesa on the California border, that is frequently used by Mexican migrant smugglers, the department said in a statement late Sunday.

The Defense Department said a militarized National Guard patrol came under fire after spotting two vehicles — a gray pickup and a white SUV — in the area, which is near an informal border crossing and wind power generation plant known as La Rumorosa.

One truck sped off and escaped. The National Guard opened fire on the other truck, killing two Colombians and wounding four others. There was no immediate information on their conditions, and there were no reported casualties among the guardsmen involved.

One Colombian and one Mexican man were found and detained unharmed at the scene, and the departments said officers found a pistol and several magazines commonly used for assault rifles at the scene.

Colombians have sometimes been recruited as gunmen for Mexican drug cartels, which are also heavily involved in migrant smuggling. But the fact the survivor was turned over to immigration officials and that the Foreign Relations Department contacted the Colombian consulate suggests they were migrants.

Cartel gunmen sometimes escort or kidnap migrants as they travel to the U.S. border. One possible scenario was that armed migrant smugglers may have been in one or both of the trucks, but that the migrants were basically unarmed bystanders.

The defense department said the three National Guard officers who opened fire have been taken off duty while the incident is being investigated.

Former president Andrés Manuel López Obrador, who left office Sept. 30, gave the military an unprecedentedly wide role in public life and law enforcement; he created the militarized Guard and used the combined military forces as the country’s main law enforcement agencies, supplanting police. The Guard has since been placed under the control of the army.

But critics say the military is not trained to do civilian law enforcement work. Moreover, lopsided death tolls in such confrontations – in which all the deaths and injuries occur on one side – raise suspicions among activists whether there really was a confrontation.

For example, the soldiers who opened fire in Chiapas – who have been detained pending charges – claimed they heard “detonations” prior to opening fire. There was no indication any weapons were found at the scene.