SAN JOSE -- A gang of brazen purse snatchers, nicknamed 'The Rippers' by police, have been targeting Asian women at South Bay malls with grab-and-dash robberies in parking lots, authorities said.

San Jose detective John McElvy said the gang strikes even when there are other people around and has pulled off at least 21 recent robberies. Police are also concerned because the threat of a knife or gun has been used in at least three robberies.

"We have had several incidents where the suspect produced a handgun or a knife," Enrique Garcia, a San Jose police spokesman. "They don't care if there is a person walking around cars nearby... it's the element of surprise."

And while four suspected members have been arrested, the brazen crimes have continued over the last several months.

On Tuesday, a woman was robbed of her purse at 7:20 p.m. as she walked through the Costco parking lot at Senter Road. It was the second time 'The Rippers' have struck in that particular spot.

"The word on the street is that if you need cash, this is an easy way to get it," said McElvy. "They seem to be going after Asian woman as easy targets."

Another spot where 'The Rippers' have struck is the Cho Senter parking lot also on Senter Road.

"At night it is not safe because there's a lot of a bad thing happening around here," Dianna Pham said at the strip mall on Thursday night.

McElvy said the reason that Asian women appear to be a target is that they carry plenty of cash.

According to police, 'The Rippers' mode of operation begins with two or three young men in hooded sweatshirts cruise a parking lot of a strip mall. They are on the lookout for a female victim to rob. In all but a single case, the victim was Asian: 19 were Vietnamese and one was Chinese.