U.S. Capitol Police Chief Phil Morse took the rare step of meeting with the House Democratic Caucus Wednesday after threats were lodged against some of the lawmakers who voted against the health care reform bill Sunday.

House Majority Whip Jim Clyburn (D-SC) indicated that at least 10 lawmakers had received threats.

House Majority Leader Steny Hoyer (D-MD) called the threats “clearly threatening in nature. Unacceptable to our society.”

At least three lawmakers have reported instances of vandalism. A glass window was shattered at the Tucson office of Rep. Gabrielle Giffords (D-AZ). A brick was thrown through the window of the Niagara Falls office of house Rules Committee Chairwoman Louise Slaughter (D-NY). And someone cut the gas line at the home of Bo Perriello, brother to Rep. Tom Perriello (D-VA).

Representatives from the FBI and House Sergeant-at-Arms Bill Livingood were present for the meeting. Livingood is in charge of security for the House. And the FBI is investigating the Perriello incident.

“I think it’s part of a pattern,” said Slaughter after the vandalism at her office. As chair of the Rules panel, Slaughter was in charge of how Democrats handled the health care bill on the floor. For a time, House Democrats were considering a unique parliamentary maneuver to pass the bill. Republicans dubbed the gambit “The Slaughter Solution.”

Reporters asked Slaughter why she thought someone would target her.

“Because he says that (the health bill) will cause civil war and next he’s going to hit everyone with a baseball bat,” Slaughter said.

In a statement, Perriello said that it was “too early to say anything definitive regarding political motivations behind this act.” A freshman who flipped a seat from Republican to Democratic in 2008, Perriello is one of the most vulnerable Democrats this election cycle. He voted for the health care bill each time.

“Here in America, we settle our political differences at the ballot box,” Perriello said.

Rep. Bart Stupak (D-MI), finally voted for the legislation after securing an agreement from the White House to prevent federal money from paying for abortions. Stupak’s voicemail system was inundated with protests, including some profane calls.

“Congressman Stupak, you baby-killing mother f***er. I hope you bleed out your a**, get cancer and die, you mother f***er,” said one message.

These incidents come on the heels of a raucous weekend on Capitol Hill where thousands of health care opponents rallied against the health care reform measure. Police detained one demonstrator after he spit on Rep. Emanuel Cleaver (D-MO). Congressional Black Caucus members John Lewis (D-GA) and Andre Carson (D-IN) say protesters jeered at them with a racial slur as they walked to the Capitol.

House Minority Leader John Boehner (R-OH) condemned the threats.

“I’m concerned about the amount of violence and anger that’s out there. It’s unacceptable,” Boehner said.“Yes, I know there is anger. But let’s take that anger, and go out and register people to vote. Go volunteer on a political campaign. Let’s do it the right way.”

After their meeting with Capitol law enforcement officials, Hoyer and Clyburn hinted that some Republicans have tried to goad some protesters.

“When people start talking rhetoric of putting people on firing lines, that rhetoric of that type, targeting their faces with crosshairs, that activity ought to be unacceptable,” said Hoyer.

In an interview with National Review, Boehner declared that fellow Ohioan Rep. Steve Driehaus (D-OH) “may be a dead man” for his vote in favor of the health care measure.

Like Perriello, Driehaus is a freshman who won a seat from the Republicans last cycle. The Congressional districts of Driehaus and Boehner are contiguous.

Clyburn suggested that Republicans should be more vocal in their denunciations of the threats, regardless of their opposition to the health care bill.

“Silence in the face of such action appears to be condoning such action,” Clyburn said.

Clyburn himself was the recipient of a fax that depicted a noose and carried a misspelled racial epithet.

“I’m not worried about this kind of stuff myself,” Clyburn said. Clyburn is one of only two African American politicians to ever serve in Congressional leadership.

U.S. Capitol Police Chief Phil Morse declined to comment after the closed door meeting with House Democrats.

Only senior House and Senate leaders of both parties receive specific security details. Security sources indicated that no special arrangements are currently being made for individual lawmakers. But in the past, those who receive threats have received special details if the situation warrants.

John Brandt and Trish Turner contributed to this report.