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California authorities on Thursday activated the CodeRed Emergency Alert System and continue to search for missing Kiely Rodni, 16, who was last seen at a party in Tahoe National Forest over the weekend.

Rodni vanished from a Prosser Family Campground party of more than 300 people, including high schoolers and young adults, just after midnight on Aug. 6 in Truckee, California. No witnesses saw her leave the Prosser Family Campground, and authorities believe the teenager may have been abducted.

"We have about an 80% enrollment for Nevada County, so out of our 100,000 residents, that message should hit about 80,000 residents," Nevada County Sheriff’s Office Capt. Sam Brown said of the CodeRed alert during a Thursday afternoon press conference.

An Amber Alert has not been issued in the case at this time because there is no evidence to confirm that Rodni was abducted.

MISSING KIELY RODNI'S MOTHER SAYS AMBER ALERT ‘SHOULD HAVE BEEN ISSUED IMMEDIATELY,’ WANTS TO STAY ‘POSITIVE’

"We have other countries that are even asking and wanting to talk to the family, so there's support, I think because people feel like they could be even in this same situation themselves. We just want word out so that more eyes are out because we don't have an exact spot to look for, and that is unusual — especially with a large object like a car," Brown said.

Additionally, investigators are asking those who went to the Prosser Family Campground party to submit photos or videos of a big fight that apparently occurred the night Rodni disappeared.

MISSING KIELY RODNI: MASSIVE SEARCH AS FRIENDS REVEAL TEEN'S LAST KNOWN FOOTSTEPS IN POSSIBLE ABDUCTION CASE

The Placer County Sheriff’s Office and Nevada County Sheriff’s Office said in a Thursday morning statement that they have put "numerous resources" to use to help find the missing girl, and "agencies have responded to help locate Kiely over the past several days."

Kiely Rodni's father, Daniel Rodni

Daniel Rodni at a community search effort for his missing daughter, Kiely Rodni. (Derek Shook for Fox News Digital)

"Searchers from across the state continue their search on the ground, in the air, and in the water — so far, we only have information on Kiely’s last known location before she went missing," they said in a Facebook post. "Detectives from local, state, and federal agencies continue to follow up on leads and conduct interviews in hopes of locating Kiely and her vehicle."

Between Aug. 6 and Aug. 10, more than 220 law enforcement personnel have been assigned to the search for Rodni, and officials have received more than 500 tips related to the case.

Rodni was last seen at a large end-of-summer high school party in the Tahoe National Forest that stretched from Friday night into the early hours of Saturday. Authorities say there is no evidence to confirm a kidnapping at this time.

Authorities have conducted search efforts since then, including dive teams that entered the Prosser Creek Reservoir on Wednesday looking near the shoreline for signs of Rodni or her silver Honda CRV, which is also missing. But they found no clues to lead them to Rodni's whereabouts. 

Police said she last spoke with friends and family shortly after midnight on Aug. 6 and that her phone was turned off around 12:33 a.m.

The phone last pinged near the Prosser Family Campground within Tahoe National Forest in Truckee at the site of a high school graduation party involving more than 300 attendees from several surrounding communities — and a few from as far away as San Francisco — plus drugs and alcohol. Authorities are still trying to find someone who witnessed Rodni leaving the party before she disappeared.

The 16-year-old was wearing a black bodysuit and Dickies pants in surveillance footage captured hours before she disappeared. 

Rodni is described as 5-foot-7 and about 118 pounds. She has blonde hair and hazel eyes. She has a tattoo on her ribs of the number "17." She has a nose ring and several other piercings. She drives a silver 2013 Honda CRV with California license plate 8YUR127. It has a small ram's head sticker on the back window, under the rear wiper blade.

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Anyone with information is asked to call the Placer County Sheriff’s Office’s dedicated tip line at 530-581-6320. Callers can remain anonymous. Those with photos and videos that may assist with the investigation into Rodni's disappearance can submit them to officials here.

The family is offering a $50,000 reward for Kiely’s return.

Fox News' Michael Ruiz contributed to this report.