Mexican authorities made “several arrests” Sunday following the November highway massacre of nine U.S. citizens in the Mexican state of Sonora.

The attorney general’s office announced that in a joint effort with the Mexican Army, Navy, National Guard and intelligence officials, they arrested multiple people they believe to be involved in the incident that left several members of the extended LeBaron family, including children, dead Nov. 4 in a drug cartel ambush.

The attorney general’s office said the violence against the family was “indescribable,” but provided scant details on the arrests, not specifying how many people were arrested or identifying the alleged suspects.

“When there is more information, reliable and trustworthy, it will be released immediately, to public opinion,” the office said in a statement in Spanish.

The victims who died while traveling in a large convoy by the Mexico border were identified as Christina Marie Langford Johnson, 30; Dawna Langford, 43; Trevor Langford, 11; and Rogan Langford, 2.

Also killed were Rhonita Miller, 30; Howard Miller, 12; Krystal Miller, 10; and the 8-month-old twins, Titus and Tiana Miller.

The nine victims belonged to an offshoot group of Mormon fundamentalists who first came to Mexico nearly a century ago.

Authorities have been under international pressure to make arrests since the massacre. In the immediate aftermath of the deaths, Mexican officials arrested a suspect who had a cache of weapons, but he was later determined to have not been a part of the killings.