( CNN ) -- Police in the Northern California town of Tracy are pursuing hundreds of possible leads in the disappearance of 8-year-old Sandra Cantu , a police spokesman said Wednesday . Sandra Cantu , 8 , disappeared on Friday , according to police in Tracy , California . Police have received 477 tips since she disappeared Friday , 100 of them on Tuesday alone , Lt. Jeremy Watney of the Tracy Police Department told reporters . `` We 're following up on all of them , '' he said . `` It 's extremely frustrating . We want her back safe . That 's the bottom line . `` At this point , everything is still open . '' Authorities Tuesday afternoon impounded and searched a car -- the fourth one to be seized -- that was parked near the mobile home park where Sandra lives and was last seen . On Monday night , Tracy police and FBI agents searched six locations , some in the Orchard Estates Mobile Home Park and some in Tracy . All of the places were connected to two men who live in the mobile home park , officials said . Watch CNN report on Sandra 's disappearance » . Authorities have not called the men suspects and have not named them publicly . They did not say how or if they might be related to the case . On Friday afternoon , Sandra came home from school , kissed her mother and left to play with a friend who lives a couple of homes away . A short time later she left that home to go to another friend 's home , a spokeswoman for her family said Tuesday . The girl , who was wearing a pink Hello Kitty T-shirt and black leggings , has not been seen since , said the spokeswoman , Lisa Encarnacion . Her parents reported her missing about 8 p.m. Friday . Officials said surveillance camera footage recorded the girl playing in the park . A dozen agencies are involved in the search . The number of searchers swelled over the weekend , and a similar effort is likely Saturday and Sunday , Watney said . Police have said they doubt she ran away . The mobile home park has fewer than 100 units . There are about 80 registered sex offenders living in a five-mile radius around it . Tracy is about 60 miles east of San Francisco , California .
NEW : Police say they ' ve received four calls -- three on Tuesday . A fourth car near mobile home park is searched for clues . Sandra Cantu played with a friend on Wednesday , headed for a second friend 's house . It 's not clear whether she ever got to the second house , family says .