A driver struck and seriously injured a woman while fleeing from angry members of the annual Zombie Walk held during Comic-Con, police said.
The driver and his family, who are all deaf, had waited for several minutes at a junction in central San Diego, as a large crowd taking part in the walk, including some in zombie make-up, went by, David Stafford said.
However, when small children in the car became frightened of the crowd, the 48-year-old driver rolled slowly forward to get through, he said.
Some crowd members became angry, surrounded the car, pounded on it, climbed on it and smashed the windscreen, he said.
The driver then sped up to flee and hit a 64-year-old woman, who fell under the car.
"Her arm was badly scraped. It's going to need surgery," he said.
Some witnesses chased the car for several blocks until the driver spotted a police officer and stopped.
The driver was not arrested but the investigation continued, Mr Stafford said.
A witness, Sean Foley, said that in his opinion the driver was at fault.
After waiting about 10 minutes, the motorist started honking his horn and inching forward into a crowd that included children and babies in pushchairs, Mr Foley said.