Several armed men shot and killed the family, authorities said. Oaxaca prosecutors told CNN the father, identified as 24-year-old Juan Alberto Pano Ramos, was carrying Marcos Miguel Pano Colón in his arms when they were shot Friday at 8:40 pm. The 17-year-old mother, identified as Alba Isabel Colón, also was killed.
The picture focusing on the baby in a bloodstained white onesie, lying head down between his father's torso and left arm, has gone viral in Mexico. The young mother, wearing denim shorts and a red blouse, lies in the background.
Many are comparing the image with that of Aylan Kurdi, the 3-year-old Syrian refugee boy whose body was found on a Turkish beach after he drowned in the Mediterranean Sea.
"Do you remember the Syrian boy
?" a Facebook account called "Solo Acapulco" asks. "Do you remember how you became indignant and even put a little flag on Facebook? Well, this happens in Mexico, in Pinotepa Nacional to be precise, where drug violence killed this family, including this 7-month-old little angel."
"Is there no indignation about [what happened] in Pinotepa Nacional?" another Twitter user asks. "Us Mexicans seem to be more compassionate about what happens to others than ourselves."
The user identified only as "Personal Jesus" puts a picture of the executed baby and his family right next to the drowned Syrian boy.
Author Octavio Martínez Michel, in an opinion column published by the website La Silla Rota (The Broken Chair) posts a Mexican flag with a drawing of the dead baby in the background.
"Is it possible to imagine anything more unjust than the cold-blooded murder of a family carrying a baby in their arms?" Martínez asks readers.
The state attorney's office said the motive appears to be drug-related.
"A rival drug gang from [the neighboring state of] Guerrero located them and had them riddled with bullets," prosecutors said in a statement to CNN, adding that the parents of the baby sold drugs.
A suspected drug trafficker identified as Isidoro Gonzáles Gerónimo, aka "El Isis," was shot and killed in Oaxaca, the same day, the state attorney's office said. The couple, authorities say, worked for Gonzáles, who operated in Guerrero.
On Saturday, the day after the killings, four people were detained in connection with Gonzáles' death.
Drug-related violence has plagued the state of Guerrero in recent years. Guerrero had 2,016 homicides last year, the most of any Mexican state, according to government figures.
That violence is spilling over into Oaxaca, where the baby's parents had recently moved, according to authorities.
The same night the family was gunned down in Pinotepa Nacional, another family of three, including a 14-year-old girl, were shot and killed in the municipality of Miahuatlán.