The C.I.A. provided intelligence to Austrian authorities that allowed them to disrupt a plot that could have killed thousands of people at a Taylor Swift concert in Vienna this month, the agency’s deputy director said on Wednesday.

David S. Cohen, the deputy director of the C.I.A., said the agency had provided information about four people connected to the Islamic State who were planning an attack. Some of the individuals arrested were found with bomb-making material and had access to the concert venue, where several shows were scheduled to take place in the days after the arrests.

“They were plotting to kill a huge number, tens of thousands of people at this concert, I am sure many Americans,” Mr. Cohen said at the annual Intelligence Summit just outside Washington, D.C. “The Austrians were able to make those arrests because the agency and our partners in the intelligence community provided them information about what this ISIS-connected group was planning to do.”

On Aug. 7, Austrian authorities arrested two people accused of plotting a terror attack; others were arrested in subsequent days. Austrian officials said one of the men, a 19-year-old Austrian, had pledged allegiance to the Islamic State and had focused on Ms. Swift’s tour as a target.

Mr. Cohen expressed no doubt that attacking the Eras Tour concert and killing a large number of concertgoers was the goal of the plot.

He did not say how the C.I.A. had learned about the planned attack. But intelligence agencies have previously alerted other countries about terrorist plots. Earlier this year, U.S. officials warned authorities in Iran and in Russia that the Islamic State’s Afghanistan-based affiliate, known as ISIS-Khorasan, intended to strike events — a memorial service in Iran and a concert in Moscow — though neither country was able to stop those attacks.