At least three U.S. residents have been killed in Ciudad Juarez, Mexico, in as many weeks as the death toll in the violent border city surpasses 1,400.

The latest victim, a 32-year-old American woman, was shot several times Tuesday as she stood in front of a Juarez home, Mexican police said. The woman was taken across the Rio Grande back into El Paso, where she died on the way to the county hospital, officials said. It wasn't immediately clear where the woman lived.

Two other U.S. residents, Roberto Martinez and Ruth Sagredo Velasco, were killed in a barrage of at least 20 shots from AK-47 assault rifles fired at them as they drove in a Nov. 22 funeral procession for Sagredo's sister.

Both Martinez and Sagredo were U.S. residents living in El Paso and working at the Texas Tech Health Sciences Center there.

The killing of Velasco, her sister Cinthia Judith Sagredo Escobedo just a few days earlier, and her father Francisco Maria Sagredo Villareal in October, were related to domestic problems, Velasco's attorney Edward Hernandez told the El Paso Times.

Juarez, a sprawling city of about 2 million, has been the site a bloody drug cartel war that has killed more than 1,400 people this year. Warring cartels have been fighting for control of the city's lucrative drug and human smuggling trade. Mexican authorities have stationed thousands of soldiers and additional police officials in the city, but the fighting has only intensified.

George W. Grayson, a Mexico expert at the College of William and Mary in Virginia, said violence in Juarez and other Mexican border cities has become so widespread in the last year that innocent bystanders are routine victims.

"It's just mounting violence and I think it's going to get much worse," Grayson said.

Grayson said violent crime has become so common that criminals unrelated to the battling cartels are also taking advantage of the virtual lawlessness.

Americans have been cautioned about traveling to Mexico.

In a travel alert issued in October, U.S. State Department officials warned that "the situation in Ciudad Juarez is of special concern." The alert warned travelers to avoid isolated areas at night or in the early morning and avoid carrying cash to the city's U.S. consulate.