Story highlights A teen advertised the party online

About 100 partiers arrived at the home

The mansion has a custom movie theater, a casino room and water slide

Suspects helped police in their investigation, police say

Teens call them ghost parties: gatherings organized on a whim -- at a house that's often not the host's.

Police say revelers at one such ghost party ransacked an opulent Southern California mansion, leaving $1 million in damages, and making off with medieval armor, designer suits and a $250,000 stuffed leopard.

That was last month. This week, Los Angeles County Sheriff's Department announced it had arrested 16 teens -- helped, in part, by photos they posted online of their late-night romp.

"They were actually bragging about the party, showing themselves within the residence, showing themselves carrying some of the stolen property," Sheriff's Capt. Tim Murakami told reporters Wednesday.

Party supposed to be outside

The party took place November 23 at a swanky $7 million mansion that was up for sale, Murakami said.

A teen tweeted that the party would take place in the vacant home's backyard. About 100 guests arrived and paid admission.

"They just had a free-for-all once the place was broken into," Lt. Arthur Scott told CNN affiliate KTLA . "Once entry was made, it was like, 'Oh, this is fun.'"

Suspects helped police

The party went on in the palatial, 9,000-square-foot place for some 17 hours.

The teens left early in the morning, authorities say, leaving the place trashed. A two-week investigation followed.

Among the evidence authorities say they used to get search warrants on homes in the area were the incriminating selfies some partygoers posted online.

"The respective warrants resulted in the recovery of stolen items, ranging from designer clothing, art affects, electronics and even a mounted snow leopard," the L.A. County Sheriff's Department said.

Three 18-year-olds along with 13 minors were arrested. They face multiple charges including burglary, grand theft and trespass.