A three-car accident on I-684 NB yesterday afternoon put the brakes on the afternoon commute. Katonah FD, along with Katonah-Bedford Hills Ambulance Corps, was dispatched around 5 p.m. to the accident that occurred near mile marker 16 in the left lane of the northbound highway. Cars 2211, 2212, 2213 and Rescue 17 responded and set up a safety zone and controlled traffic while police and EMS personnel tended to those involved in the accident. A child and a motorist were both transported to Northern Westchester Hospital for observation. All lanes of the road were re-opened in about an hour.