Cambridge police are seeking witnesses to a fatal accident Tuesday involving a loose hose on a Cambridge Fire Department engine.

The engine — lights and siren on — was responding to a call on Pleasant Street near Central Square, driving down Massachusetts Avenue and taking a left turn onto Western Avenue at 11:40 a.m. Tuesday when a hose became dislodged and began to trail behind the vehicle, said Jennifer Flagg, a police spokeswoman.

During the left turn, witnesses said, the trailing hose whipped around and hit Gertrude King, 82, of Somerville, who was standing on the median island as the engine passed.

Cambridge Fire Rescue took the injured woman to Massachusetts General Hospital. She underwent surgery but died today at 2:36 a.m.

Cambridge police are investigating the accident, and the Middlesex County District Attorney’s Office has been notified, Flagg said.

Police officers have leafleted the intersection where the accident occurred, asking for anyone who may have seen the accident to call (617) 349-9323.