United Talent Agency was the victim of a computer hack that severely disrupted business at the agency on Tuesday, shutting down email, causing meetings to cancel and forcing staff to work on their personal devices, numerous individuals told TheWrap.

Frustrated clients found their emails and phone calls going unanswered all day as the agency struggled to deal with what appeared to be a deliberate cyberattack. The agency instructed its staffers to use their smartphones and personal devices until further notice, which prevented them from accessing contacts and information stored in company systems.

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In a statement to TheWrap, a UTA spokesman said:

“On Monday, UTA was the subject of a malware incident — an unfortunate yet common reality of our digital world that can take place regardless of the strong safeguards a company has in place. Most importantly, we have no reason to believe any private information about the agency, its employees, or its clients has, in any way, been compromised.”

The spokesman said UTA was working with computer experts to resolve the situation. An agency executive said they were not sure if the malware was a deliberate attack, but were investigating.

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He added: “In the interim, every member of our team continues to have access to their email and phones, and the situation is being resolved.”

A virus affected computer terminals at the UTA’s Beverly Hills headquarters, resulting in cancelled meetings set for their clients and other businesses like talent management companies, two knowledgeable individuals said.

“A ton” of calls were “cancelled and pushed,” a colleague at another talent company told TheWrap.

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Additionally, a widely-used industry database called inEntertainment — which logs production, maintains contacts and schedules meetings — was rendered unavailable to the agency, causing a ripple effect that slowed work at other talent and management firms.

However, an inEntertainment spokesperson tells TheWrap that any outage was specific to UTA and no other customers were affected. “inEntertainment was unaffected by the malware attack at UTA,” the spokesperson said. “Our servers were fully operational and no other customers experienced an interruption in service.”

Staffers at UTA were stymied, and one insider told TheWrap that the hackers were demanding a ransom of 25,000 Bitcoins, the equivalent of $30 million. The executive denied there was a ransom request, but acknowledged being aware of a rumor of ransom. The rumored amount was much lower, the executive said, a Bitcoin equivalent of $25,000.

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The executive described the disruption as a computer “virus,” and insisted that business was being conducted as usual. The executive said that New York, Nashville and London satellite offices were not affected.

UTA represents stars like Chris Pratt, Angelina Jolie and Gwyneth Paltrow.

If confirmed, the hack would be the latest in a series of cyberattacks on major companies, and the biggest since Sony was hacked in a devastating shutdown of the studio in 2014.

This post was updated with additional information after publication.