CIUDAD JUAREZ, Mexico -- U.S. consular officials on Thursday said that both Texas university students killed in Ciudad Juarez earlier this week were U.S. citizens, bringing the number of Americans slain in the violent border city to six in as many days.

Officials had earlier confirmed that one of the dead University of Texas at El Paso students was an American, 23-year-old Eder Diaz. The U.S. Consulate in Ciudad Juarez said in a statement e-mailed to The Associated Press on Thursday that the other UTEP student, Manuel Acosta, also was also a U.S. citizen.

The two were attacked Tuesday by gunmen who opened fire on their car. Acosta, 25, was killed at the scene, while Diaz died early Wednesday at a Juarez hospital.

Both were students at the university's College of Business Administration and had been on campus shortly before they were killed, though they lived in Juarez, just across the border from El Paso.

Manuel Acosta was on pace to graduate early next year and Diaz had transferred recently from a community college.

Richard Adauto, UTEP executive vice president, said the university has considered providing emergency temporary housing in El Paso for students from Juarez. He said many already had moved to Texas due to the violence at home.

Killings of U.S. citizens are on the rise in Mexico, which has seen more than 28,000 deaths in the past four years of its battle with organized crime.

U.S. State Department spokesman Philip Crowley said Thursday that 84 U.S. citizens have been killed this year in the border state of Chihuahua, where Ciudad Juarez is located.

Officials in Juarez have not said if the recent deaths of the U.S. citizens are linked.

Luis Carlos Araiza, 15, a student at Bowie High School in El Paso, and Joanna Herrera, 27, were fatally shot while traveling in a BMW sport utility vehicle near the Zaragoza international bridge Saturday. Mexican officials said they had criminal records but would not elaborate.

Edgar Lopez, 35, was shot and killed Saturday at a residence in Ciudad Juarez, while on Friday, Lorena Izaguirre, 24, was killed at a tortilla shop.

Ciudad Juarez has become one of the world's deadliest cities amid a turf war between the Sinaloa and Juarez drug cartels. More than 2,000 people have been killed this year in the city.

The state department has issued a travel warning for several parts of Mexico, including Chihuahua state, adding that Ciudad Juarez is of special concern.