A Florida postal worker who piloted his gyrocopter through Washington airspace for 30 miles to land at the U.S. Capitol had weapons aimed at him and "should have been blown out of the air," a senior lawmaker said after a briefing on the incident Wednesday.

Doug Hughes, 61, is "lucky to be alive" after it was revealed authorities had guns trained on him, but they made the decision not to shoot him down out of concern for injuring people on the ground, Rep. Jason Chaffetz, R-Utah, chairman of the House Oversight committee, told reporters.

"He is lucky to be alive, because he should have been blown out of the air and very well could have been," Chaffetz said.

The closed-door briefing of House members by the Secret Service and Capitol Police came just days after the incident that exposed a gap in the government's efforts to ensure the security of the White House, Capitol and other critical buildings in Washington.

Chaffetz said security tracked Hughes as he approached the Capitol last week after taking off from Gettysburg, Pennsylvania. A "judgment call" was made not to shoot Hughes down, Chaffetz said. Rep. Elijah Cummings, D-Md., said officials were concerned about injuring people on the ground if an attempt was made to shoot down Hughes.

Chaffetz said a combination of "lack of communication and some human error" by Capitol Police and other officials allowed Hughes to steer his tiny aircraft within a few hundred feet of the Capitol before landing on the West Lawn.

Chaffetz said he was deeply concerned at "a lack of coordination and communication" among law enforcement agencies charged with what he called "a no-fail mission" to protect the Capitol and other important sites in Washington, including the White House.

Cummings called the incident a "wake-up call" to all law enforcement agencies involved, and called for a "transformative moment." 

Capitol Police, the Secret Service and other agencies operating in silence need "to look very carefully at what happened here, dissect it, figure it and use this to make things better," Cummings said, emphasizing that he wants the agencies to learn to work together on protecting the White House and the Capitol.

"Lives depend on it," Cummings said. 

Cummings and Chaffetz said they were outraged that members of Congress were not alerted to the potential security threat even as parts of the Capitol complex were placed under lockdown.

"That's inexcusable," Chaffetz said.

Chaffetz and Cummings said they will hold a hearing on the incident next week with representatives of six agencies: the Secret Service, Capitol Police, Congress' Sergeant at Arms, the Federal Aviation Administration, North American Aerospace Defense Command (NORAD) and the U.S. Park Police.

Three of the agencies -- the FAA, NORAD and the park police -- were no-shows at Wednesday's briefing, irking lawmakers.

"They've got a lot of explaining to do" about why they did not attend the briefing, Chaffetz said.

Lawmakers were told during the briefing that "incursions" into the restricted air space around Washington occur nearly every day and are usually "dealt with in a smooth and professional manner," Chaffetz said, in stark contrast to the gyrocopter incident.

Lawmakers raised alarms about security after Hughes' stunt, which was aimed at drawing attention to campaign finance reform.

Homeland Security Secretary Jeh Johnson said last week that Hughes "literally flew under the radar" to the Capitol lawn, but added that it's too soon to say whether security changes are needed.

"We are a democracy. We don't have fences around our airspace, so we've got to find the right balance between living in a free and open society, and security and the protection of federal buildings," Johnson said.

Chaffetz said there is a "heightened awareness" about the risks of small aircraft in the wake of the gyrocopter stunt.

Anyone who enters restricted airspace now will have "a major problem," Cummings said.

Hughes was charged with two federal crimes, violating restricted airspace and operating an unregistered aircraft. The crimes carry penalties of up to four years in prison and fines.

The Associated Press contributed to this report.