Trash cans, couches, signs, newspaper racks, and other items were thrown into the bonfires by large crowds of people at 16th and Valencia, 19th and 22nd streets. Firefighters had to be escorted in by riot police to fight some of the fires.
Police spokesman Officer Carlos Manfredi said police were deploying units to hot spots around the city. "Obviously the crowd is celebrating and spilling over into the streets, so we're making sure everybody stays safe and nobody gets injured," Manfredi said.
The celebrations caused street closures and significant delays for traffic and public transit according to the Department of Emergency Services.
The city of San Francisco plans to hold a ticker tape parade and civic celebration in honor of the Giants on Wednesday, also Halloween. Mayor Ed Lee announced the parade will start at 11 a.m. at the foot of Market Street and continue to Civic Center Plaza.
The Giants swept the Tigers, winning the series in Game 4 in Detroit Sunday night with a 4-3 victory. It is the team's second World Series win in three years.
"The rain in Detroit couldn't dampen the drive, talent and determination of the San Francisco Giants team tonight," Lee said in a statement tonight. "Once again, the Giants brought our City together as we all cheered on our hometown heroes to another remarkable World Series victory."
The team will arrive at SFO at 3 p.m. today.
Bay City News contributed to this report.