Washington - The pitched battle over health-care reform has unleashed a rash of political vandalism and attacks, with at least 10 Democratic members of Congress reporting death threats, incidents of harassment or vandalism at their district offices over the past week.

More than 100 House Democrats met behind closed doors Wednesday afternoon with the FBI and U.S. Capitol Police. The lawmakers voiced what one senior aide who was present described as "serious concern" about their security in Washington and in their home districts when they return this weekend for spring recess.

Usually only members in leadership positions have regular personal protection by the Capitol Police. But at least 10 members have been offered increased protection by law enforcement agencies, House Majority Leader Steny Hoyer, D-Md., said.

Asked if members are endangered, Hoyer said: "Yes. (There are) very serious incidents that have occurred."

Senate Sergeant-at-Arms Terrance Gainer e-mailed senators and staffers Wednesday telling them to "remain vigilant." He said in an interview that the warning was meant to "assuage people's fears." Despite the incidents involving House members, Gainer, a former Capitol Police chief, said there have been no reported incidents involving senators.

The vandalism began last weekend, when the House debated the health bill for final passage. In Wichita, Kan., someone broke the window of a storefront county Democratic Party headquarters with a brick that had "No to Obama" and "No ObamyCare" written on it. Lyndsey Stauble, executive director of the Sedgwick County Democratic Party, said she came to work Saturday morning to clean up the shattered glass strewn about her desk.

"It was surprising and alarming to know that people, when they have so many opportunities for expression in this country, that somebody would resort to a brick," Stauble said.

Over the next 24 hours, thrown bricks shattered the glass doors and windows of party headquarters from Rochester, N.Y., to Cincinnati. A gas line at the Charlottesville, Va., home of the brother of Rep. Tom Perriello, D-Va., was severed Tuesday after a self-identified "tea party" activist posted what he believed to be the Virginia Democrat's address on a Web site and urged opponents to "drop by" to convey their opposition to his yes vote on health care.

Rep. Louise Slaughter, D-N.Y., had a brick thrown through her Niagara Falls district office and received a threatening voicemail referencing sniper attacks. Rep. Gabrielle Giffords, D-Ariz., had the front door to her Tucson district office shattered. And Rep. Bart Stupak, D-Mich., whose last-minute negotiations to bar federal funding of abortion helped secure the bill's passage, received a fax with a drawing of a noose and an anonymous voicemail saying, "You're dead. We know where you live. We'll get you."

In Washington on Wednesday, the attacks were roundly condemned, with some congressional leaders wondering whether the long fight over health-care reform had unleashed an ugly dimension to the modern political discourse.

"If we fail to learn the lessons of our history, we are bound to repeat them," House Majority Whip James Clyburn, D-S.C., said. "I think all of us learned some great lessons from the '60s and '70s, and there are some lessons that none of us want to repeat, but one thing we know, as Steny Hoyer said, "Silence is consent.' "

House Republican Leader John Boehner, R-Ohio, said the violence is unacceptable.

"I know many Americans are angry over this health-care bill, and that Washington Democrats just aren't listening," Boehner told Fox News Channel. "But, as I've said, violence and threats are unacceptable. That's not the American way. We need to take that anger and channel it into positive change. Call your congressman, go out and register people to vote, go volunteer on a political campaign, make your voice heard - but let's do it the right way."

Some Democrats, sensing a political opportunity, suggested that Republicans were fanning the violence with their fiery comments in recent days. Several GOP lawmakers stood on the speaker's balcony at the Capitol overlooking a tea party protest last weekend holding up signs that read "Kill the Bill." Below them, protesters were yelling "No! No! No!" and "Nancy, you will burn in hell for this!"

One of the more threatening incidents involved Perriello, whose older brother, Bo, came home on Tuesday and smelled gas in the house. He discovered that a line to a propane tank on a gas grill in his yard had been cut. A threatening letter was also sent to the home that day. Federal and local authorities were investigating the incident.

"While it is too early to say anything definitive regarding political motivations behind this act, it's never too early for political leaders to condemn threats of violence, particularly as threats to other members of Congress and their children escalate," Perriello, a freshman who faces a tough reelection fight, said in a statement. "And so I ask every member of House and Senate leadership to state unequivocally tonight that it is never OK to harm or threaten elected officials and their families with anything more than political retribution. Here in America, we settle our political differences at the ballot box."

Virginia Gov. Bob McDonnell and Attorney General Ken Cuccinelli, both Republicans, condemned the vandalism and threats. Cuccinelli, who has become a conservative folk hero for filing suit over the health-care bill, said the severing of the gas line was "absolutely, totally unacceptable" and that posting Perriello's address online was "way over the line."

Some of the violence appears to have been instigated by an Alabama blogger, Mike Vanderboegh, who encouraged his readers to throw bricks at the windows of Democratic headquarters across the country. Vanderboegh, a former leader of the Alabama Constitutional Militia who is headlining an open-carry gun rally in Northern Virginia next month, issued a call to the modern "Sons of Liberty" on his libertarian political blog to break windows nationwide to display opposition to health-care reform.

A vandal threw a brick into the glass doors at the Monroe County Democratic Committee's headquarters in Rochester overnight Saturday, attaching a note that quoted Barry Goldwater: "Extremism in defense of liberty is no vice."

Vanderboegh did not respond to questions Wednesday from The Washington Post, but he took credit for the incident in an interview earlier this week with The Rochester Democrat and Chronicle. "I guess that guy's one of ours," he told the newspaper. "Glad to know people read my blog."

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Staff writers Ann Gerhart, Paul Kane, Anita Kumar and Rosalind S. Helderman and research editor Alice Crites contributed to this report.