Street vendors have been the victims of a string of recent robberies throughout the city of Pomona.
Since April, 25 vendor robberies have been reported and police suspect many more crimes have gone unreported, perhaps because the mostly Latino vendors fear the police or because they are in the United States illegally.
Eight people have been arrested for individual vendor robberies.
Pomona Police Detective John Falls said the hardest part of investigating the robberies is tracking down the vendors afterward.
Police say vendors are easy targets because they work alone and don't have cars to jump into for protection.
The vendors, who roam residential streets and parks from about noon until 8 p.m., are usually dropped off in Pomona from other cities by their company's owners, said police Lt. Greg Hamill.
Vendors have been threatened with guns, knives and physical force, he said.
Police have distributed flyers to all of the owners of the vending companies, warning them that their employees might be in danger. They have also set up surveillance.
Hamill said that the robbers approach the vendors in groups of two or three, pretending to be customers. Vendors are usually robbed in the afternoon, he said.
Last year, a vendor was hit with a brick and killed during a robbery on San Francisco Street.