View photos from HARD Haunted Mansion in our Friday night and Saturday night slideshows.

About 50 arrests were made at the biggest Halloween dance parties over the weekend, including HARD Haunted Mansion Friday and at Monster Massive Saturday, Los Angeles police told L.A. Weekly.

Lt. Darrell Belthius of the Los Angeles Police Department's Southwest Division said about “95 percent” of the weekend party arrests involved gatecrashers, mostly at Monster Massive at the Los Angeles Coliseum because trespassing was more difficult at Hard Haunted Mansion at the nearby Shrine Auditorium Friday and Saturday.

He said the DJ-driven Monster Massive had a capacity of 80,000 and was near it. He said Hard had a capacity of 8,000 each night and was also near it. If true, nearly 100,000 revelers descended on the Exposition Park area alone to enjoy electronic dance music on Friday and Saturday.

Hard organizer Gary Richards says the capacity was more like 9,000 and that it was reached both nights. He says the party did have some gatecrashers and counterfeit ticket sellers on Friday but that, after they realized their schemes wouldn't be easily undertaken at the Shrine, they didn't return for the second night of Hard Saturday.

That night, by the way, featured surprise performances by Deadmau5 and 2 Many DJs, both of which topped Friday's bill.

Richards paid close attention to security after his Hard Summer event was shut down by Inglewood police when gatecrashers and rowdy party-goers made things raucous there in August.

Some of the more interesting alleged crimes at the weekend parties included robbery, narcotics sales, theft and interference with a lawful business, which the LAPD's Belthius says “is like trespassing.”

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