Federal lawmakers from the suburbs say a shooting near the Capitol kept them locked in place for about a half hour before they were given the all clear.
Several took to social media to say they were fine and to thank people for their concern.
"I'm OK. Happened to be on the House floor when the shots happened," U.S. Rep. Tammy Duckworth tweeted. "I'm sheltering in place."
Duckworth, a Democrat from Hoffman Estates, was preparing to speak in favor of a motion and was held in a room just off the House floor, her spokesman, Anton Becker, said.
Shortly after authorities gave the all-clear, the House resumed and Duckworth spoke, Becker said.
Staff members for other lawmakers said they stayed in their offices while the Capitol was locked down.
"Thank you for checking, myself and my office staff are safe," U.S. Rep. Jan Schakowsky, an Evanston Democrat, posted on Twitter. "We are told to stay in our office."
A spokesman for U.S. Sen. Mark Kirk said he was at the World War II Memorial blocks from the Capitol when shots were fired. He said it was calm at the monument except for sirens of vehicles heading toward the Capitol.