The eighth annual "Great San Francisco Pillow Fight" started at 6 p.m. Thursday and ended with the Justin Herman Plaza being covered in feathers, synthetic pillow stuffing and other debris, Bay City News reported. Hundreds of people participated in the event.
At about 10 p.m. Thursday, a cleaning crew moved into the plaza to sweep up feathers and used steamer machines -- a job that cost the city between $4,000 and $5,000, Department of Public Works spokeswoman Rachel Gordon estimated.
"It's messy but becoming a regular San Francisco Valentine's Day experience," Gordon said.
The cleanup process has become easier over the years as the department becomes more experienced in clearing out the feathers, Gordon said.
Notable deaths of 2014 [PHOTOS]