Martinez and Sagredo both worked at the Texas Tech Health Sciences Center in El Paso, hospital officials said.
Mexican authorities said at least 20 bullets, believed to have been fired from an AK-47 assault rifle, were fired at the 2004 Kia Amanti they were in. No arrests have been made in the case.
Juarez, a sprawling border city of about 2 million people across the Rio Grande from El Paso, has been plagued by violence amid an ongoing drug cartel war that has killed more than 1,300 people this year.
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