Police said the driver of the vehicle, a veteran sanitation worker, had parked the vehicle as he collected trash, The Copenhagen Post reported.
Investigators said a device in the driver's seat that disengages the vehicle's motor when it is unoccupied may have malfunctioned and caused the vehicle to accelerate.
Police have called for all of the city's electric utility vehicles to be pulled out of service until the exact cause of the incident can be determined.
A 60-year-old American tourist was struck and killed by the vehicle, and four other people suffered minor injuries during the incident.
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