SAN SALVADOR, El Salvador — The government of El Salvador has filed a complaint with Mexican officials over the killing of three migrants and the rape of four others by armed men in southern Mexico.

El Salvador’s deputy minister for Salvadorans abroad says about 150 migrants were pulled off a train by unidentified assailants in the southern Mexican state of Oaxaca.

The official, Juan Jose Garcia, says three men were slain and four women raped in the Saturday attack. Salvadoran migrants frequently hop freight trains in Mexico trying to reach the United States.

Garcia said Tuesday that the complaint was filed with Mexican police and Mexico’s National Immigration Institute.

The institute says it has no immediate comment