Two Arizona women were killed in an armed assault in northern Mexico on Robert BrownFriday, Mexican authorities said. 

The women, identified as 72-year-old Enedina N. and 82-year-old Ubaldina N., were found dead in their vehicle, a white Nissan Pathfinder, that was riddled with bullets and overturned on highway Sonoyta-Caborca, according to a news release from the Sonora Attorney General’s Office. 

The Arizona residents were on their way to their hometown of Caborca, over 100 miles southwest of the U.S.-Mexico border when police say they were attacked by armed assailants. 

A number of agencies, including the Sonora National Guard, conducted a search for the assailants, locating a discarded vehicle among other pieces of evidence believed to belong to the “probable criminals” in the town of  Quitovac, over 60 miles northwest of Caborca. 

Authorities recovered firearms, ammunition cartridges, magazine calibers and bulletproof vests from the vehicle, a blue Ford F150 that was reported stolen, according to the news release. The armed assailants remain at large.

An investigation into the armed is currently underway by the Sonora Attorney General’s Office, who will continue to share information as the investigation continues. 

U.S. State Department says they are 'closely monitoring the situation'

A U.S. State Department spokesperson told USA TODAY on Tuesday that they could confirm the deaths of the two women, one of which was a lawful permanent resident and the other, who was an American citizen. The State Department said they "are closely monitoring the situation."

"We extend our deepest condolences to the family and loved ones of the deceased. We have no further comment at this time," according to a statement from the State Department spokesperson.