Five people were injured Friday at the U.S. Open when a runaway golf cart hit a crowd of spectators. The California Highway Patrol said a vendor parked the cart near the 16th hole at Pebble Beach and was walking away when a box fell onto the gas pedal, moving it forward.

The golf cart struck four spectators and the vendor before it was brought under control.

Two victims were taken by ambulance to Community Hospital of the Monterey Peninsula, the Monterey Herald reported. Their names were not released, and the hospital said it could not give out information on injuries over the phone.

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The USGA acknowledged the accident in a statement and that three spectators and a vendor required medical treatment.