FBI Director James Comey conducted a classified briefing with four top senators on Capitol Hill on Wednesday afternoon after lawmakers demanded details on whether the agency was investigating ties between Russia and Donald Trump's presidential campaign.

The meeting, which lasted about an hour, was held in a secure room in the Senate basement and was attended by Judiciary Committee Chairman Chuck Grassley, R-Iowa; the committee's ranking member, Dianne Feinstein, D-Calif.; Mark Warner of Virginia, the top Democrat on the Senate intelligence committee; and Minority Leader Chuck Schumer of New York.

Comey ignored shouted questions from reporters as he left the Capitol following the briefing.

Sens. Feinstein and Grassley addressed reporters, but divulged few details.

"The chairman and I had written a letter asking for a briefing on certain topics, which I'm not going to go into, and because of the strength of the chairman's tough language, we were able to have a briefing," Feinstein said. "This briefing was all on sensitive matters and highly classified, and it's really not anything we can answer any questions about."

When asked, Feinstein refused to answer whether Comey confirmed the existence of an investigation into Trump or his allies and alleged contacts with Russian officials.

"I'm not going to answer any questions on it – I don't want to be rude to you, nor does the chairman," Feinstein said. "You've been standing here for a long time. I know how I would feel, my feet would hurt. I'm sorry, but it's the way life is here."

Feinstein and Grassley wrote to the Justice Department in February following the resignation of Michael Flynn as Trump's national security adviser. Flynn left his position after it was discovered he had spoken to Russian Ambassador Sergey Kislyak about U.S. sanctions ahead of Trump taking office, and then misled Vice President Mike Pence about the nature of those discussions.

Connections also have been reported between Russian figures and new Attorney General Jeff Sessions ; White House adviser and Trump son-in-law Jared Kushner ; campaign foreign policy adviser Carter Page ; campaign national security adviser J.D. Gordon ; and former campaign chairman Paul Manafort . Informal Trump adviser Roger Stone also had contact with a hacker persona believed to have been used by Russian intelligence.