LOS ANGELES — An annual spring party in a Southern California beach town devolved into a riot last month when revelers turned violent, rocking cars, smashing windows and throwing rocks. Dozens were injured and about 50 people ended up in the hospital, including several police officers.

Today, as authorities seek help with the investigation in Isla Vista, they’re employing a new online and mobile app that designers say was created specifically for this type of situation.

“When the public really wants to catch these bad guys as badly as we do, this is the mechanism,” said Los Angeles Sheriff’s Cmdr. Scott Edson, who helped conceptualize the system in the aftermath of the Boston Marathon bombings. “They can help us by sending us pictures and video.”

The innovation, known as LEEDIR, the Large Emergency Event Digital Information Repository, pairs an app with cloud storage to help police use smartphones as tools to gather evidence.

Proponents say the crowdsourcing system gives authorities a secure, central repository for the countless electronic tips that can come in during a crisis. And since it uses remote database servers that police access online, floods of data won’t cause system crashes or be expensive to store. Most agencies, Edson said, “don’t have lots of bandwidth lying around.”

Privacy advocates criticize the app as overly broad, saying it subjects innocent people to police scrutiny and probably won’t produce much good evidence. “There’s a reason that we pay professionals to work in police departments,” said Nate Cardozo, a civil liberties attorney with the Electronic Frontier Foundation.

“And there’s a reason we don’t crowdsource photo lineups and the like — crowds aren’t good at it,” he said.

Edson says he took note during the aftermath of the Boston attacks last year when authorities were inundated with videos and photos from people at the scene of the blasts. He figured a new tool could help streamline digital evidence gathering. “It seemed like the perfect opportunity to go to the private sector,” he said.

Edson connected with Culver City, California-based tech startup CitizenGlobal Inc. and Amazon Web Services to design the system as a public-private partnership offered free to authorities and members of the public.

“With tens of millions of smartphones in use in the U.S., it’s a virtual certainty that citizens will be taking videos and photos at any terrorist attack, large-scale emergency or natural disaster,” CitizenGlobal co-CEO George D. Crowley Jr. said in a statement when the system was announced in November.

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