America's top pedestrian safety expert has been run over and killed by a bus.
Susie Stephens was an expert on bicycle and pedestrian safety on US roads.
She was crossing a road in St Louis when she was knocked down by a city tour bus. She was in the city advising a cycling and walking conference on safety.
Ms Stephens, 36, a full time safety consultant, lived in Winthrop, Washington State. She was a cyclist and leading bicycling advocate.
William "Bill" Wilkinson of the National Centre for Bicycling and Walking said: "She was one of those people who was a bright light in any group."
Friends in Washington called her a passionate cyclist who commuted to work on a bike, pedalled on Seattle's hills for years and rode bike tours in Australia and New Zealand, the St Louis-Post Dispatch reports.
Louise McGrody, program manager of the Bicycle Alliance of Washington, said: "She was very passionate about bicycling. When she found a cause to take up, look out. She was like gangbusters."
The driver of the bus told police he did not see Ms Stephens as he made a left turn.