Some Democrats said that Friday’s events had confirmed their fears that easing security too soon could leave the grounds vulnerable to attack.

“I recognize that the fence is a disturbance,” Mr. Ryan said. “It’s an eyesore. It sucks. Nobody wants that. But the question is, is the environment safe enough to be able to take it down?”

He said that lawmakers were exploring the security practices at other capitals — including a call with Israeli officials about how they protect the Knesset — as part of potential permanent security changes on the complex.

“I think everything is going to be re-evaluated after today,” he said.

Reporting was contributed by Adam Goldman, Zolan Kanno-Youngs, Luke Broadwater and Glenn Thrush.