4 relatives, including 3 Americans, shot in Mexico; 3 adults dead, child in critical condition

Four family members, including three Americans, were shot in an attack in Durango, Mexico, that left three of the four relatives dead, officials said.

The three adults were all killed: two brothers who are U.S. citizens, Vicente Peña Rodríguez and Antonio Fernández Rodríguez, and their relative, who is a local resident, Jorge Eduardo Vargas Aguirre, the Durango Attorney General’s Office said.

Vicente Peña Rodríguez's son, a minor, survived, and is in critical condition, the attorney general's office said.

The attack unfolded on Friday night as the family was traveling in a GMC Yukon with an Illinois license plate, officials said. The SUV was found on the side of the Francisco Zarco highway.

Authorities are investigating whether robbery was a motive, according to the attorney general's office.

Vicente Peña Rodríguez lived in Chicago and was in Mexico for a vacation with his teenage son, according to Chicago ABC station WLS.