LOS ANGELES, Aug. 2 (Xinhua) -- One woman was killed and four others were injured when a coastal bluff collapsed on Friday afternoon onto a group of beachgoers in city of Encinitas, 170 km south of Los Angeles.

"The City's Sheriff and first responders are on the scene assisting in rescue operations," the San Diego County Sheriff's Department tweeted.

The local Fox 5 news channel reported three people were dug out underneath the collapsed bluff by rescuers and sent to hospitals, while a fourth person who suffered minor injury declined medical treatment.

Local authorities said on their official website that sandstone bluffs and cliffs situated along the city's coastline are some of the unique features that distinguish local beaches from others in the county.

"Because of frequent bluff failures, a great deal of consideration has been given to ensuring the safety of those who visit our beaches," the authorities said. "Please be aware that in most areas hiking near or directly on top of the bluffs is prohibited. It is also important for visitors to avoid standing or sitting directly underneath unstable bluffs, since they may collapse."