Media outlets in Dallas are reporting a police officer riding a motorcycle escorting Democratic presidential hopeful Hillary Clinton's motorcade crashed and was killed.
The identity of the officer has not been released.
The crash happened just before 9:30 a.m. as the motorcade was on the Houston Street viaduct on its way to a rally in Oak Cliff.
"We are just heartsick over this loss of life in the line of duty," Clinton said. "I have asked that my condolences be conveyed to the family. I am going to call them as soon as it's appropriate, and I have placed a call to the chief of police expressing my sympathy."