Several individuals connected with a family massacre in northern Mexico were detained in an early Sunday operation. Mexican President Andrés Manuel López Obrador's office confirmed to CBS News that three suspects were captured Sunday in a joint operation by the Prosecutor General, the National Guard and the National Center for Intelligence.

Nine U.S. citizens — three women and six children — were murdered November 4. The victims were members of the LeBaron family who were part of a group of fundamentalist Mormons who migrated to Mexico after polygamy was outlawed in the U.S. in the 1800s. The operation, carried out in collaboration with the FBI, follows an earlier arrest last month, according to officials. Four people are now in custody in connection with the attack.

The LeBaron family have a history in the country that dates back generations, and includes encounters with drug cartels. Many of the family members are dual citizens, and speak both English and Spanish.

The victims in November's attack were part of the extended LeBaron family. A relative said they lived on a ranch in La Mora, a small community with a population of less than 1,000 dual U.S.-Mexican citizens. The ranch is located in a desert valley in Sonora, Mexico, about 70 miles south of Douglas, Arizona.

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One the day of the attack, the victims left their community at the same time in three separate cars, some were traveling back to the U.S., some to a neighboring town for a wedding. Suddenly, the convoy of SUVs was sprayed with gunfire. There were so many rounds fired that family members said one of the cars exploded.

It would not be the first time that members of the break-away church had been attacked in northern Mexico, where their forebears settled decades ago. In 2009, Benjamin LeBaron, an anti-crime activist who was related to those killed in the attack, was murdered in neighboring Chihuahua state, where many members of the extended LeBaron family had previously settled.

Sunday's arrest of the individuals comes the same day as thousands of Mexicans packed into the capital's central square to celebrate López Obrador's first year in office. Thousands others marched down the city's main avenue to protest violence and other issues in the country.

The Associated Press cites polls that say more than half of Mexicans support the way López Obrador has been running the country, even though homicides have risen and the economy is nearing a recession.

"We have to work together to find a way to stop the violence," one of the protesters told AP. "If we're not capable of defending life in our country, we will never be a civilized country much less a free country."

Last week, President Trump said he plans to designate Mexican drug cartels as terrorist organizations, which raised concerns in Mexico that the U.S. would launch operations on Mexican land.

López Obrador on Sunday thanked Mr. Trump for respecting Mexico's sovereignty and promised to deliver justice while emphasizing that Mexico will not accept "any intervention" by U.S. authorities.