Heightened fears about a series of burglaries and fires targeting abortion and OB-GYN clinics around metro Atlanta have triggered heightened security across the country.

The FBI, which is leading a joint investigation, , is looking at the cases as possibly domestic terrorism or civil rights violations, according to ATF spokesman Richard Coes.

"We are concerned about the escalation and activity,” said Vicki Saporta, president of National Abortion Federation, which sent out notifications to all member clinics about the Atlanta incidents twice this week, urging them to take additional precautions. "It’s not a good sign when one arson follows another, after following several burglaries. Something clearly is escalating there and we’re hoping that the strong law enforcement so far can stop it."

The National Abortion Federation is also sending a two-person security team of paid staffers to Atlanta on Wednesday to help law enforcement and the clinics. Each of the four clinics targeted here are linked to doctors who either visited the state Capitol or voiced concerns to lawmakers about new abortion restrictions that were signed into law this month.

Emmett said the investigation is in an early stage and investigators are urging the public to come forward with any information about the fires. The latest arson was the most brazen one, occurring during business hours Wednesday morning at Alpha Group GYN, which provides abortion services and counseling, on Powers Ferry Road in Marietta.

Another suspicious fire on Sunday occurred at the Atlanta Gynecology and Obstetrics Gwinnett office in Lilburn, which also was the site of a burglary on Jan. 26. The thieves stole a desktop computer.

Two other burglaries at obstetrics and gynecology offices occurred in March in Sandy Springs and unincorporated Suwanee. Most of the clinics do not perform abortions.

When asked whether authorities were worried about the fires escalating into violence, FBI Special Agent Stephen Emmett said “Yes, the fact that we have initiated a federal investigation into the matter speaks to that concern.”

One of the affected doctors, who spoke on condition of anonymity Thursday because of ongoing safety concerns, was appreciative that authorities have now stepped up their attention to the case. The doctor broke into tears.

"The charred baby pictures on the wall just broke my heart," the doctor said of the snapshots the office displayed of babies it delivered. "I don't understand the connection, but it's hard to ignore the chain of events. I think we all need to be careful until this person is caught."

Other local women's reproductive health clinics were being alerted to the situation even before they had a chance to call the police and ask, according to Jaime Chandra, a communications manager for Feminist Womens Health Center in DeKalb County.

Chandra said marked and unmarked police cars have been driving by their office all day. The clinic is taking extra security precautions, Chandra said.

“Unfortunately this is not the first time this has happened in the world of clinics nor will it probably be the last,” Chandra said.

Many long-time Atlanta residents remember all too well the bombing of a Sandy Springs abortion clinic in 1997 that was orchestrated by Eric Robert Rudolph. He later became infamous as the Olympic Park bomber.

Jack Killorin, a retired ATF agent who helped work on the Rudolph case and a former agency spokesperson, said that the heydey for abortion clinic violence was in the 1980s and 90s. While the abortion debate remains strong, crimes against abortion clinic operators have largely tapered off, he said.

According to Killorin, these types of acts historically don't involve large conspiracies, but one or a small number of disaffected people. The individuals usually don't have criminal records, since they aren't motivated by profit, but by ideology. The culprits are typically not affiliated with organized anti-abortion groups. Instead, they often believe those organizations are all talk and no action, Killorin said.

"This could very well be a lone wolf actor glorying in their powerful secrecy," Killorin said. "And if so, they are very hard to find."

Incidents of violence against abortion providers in the United States and Canada

2004: 152

2005: 761

2006: 474

2007: 249

2008: 237

2009: 187

2010: 95

* Source: National Abortion Federation. Acts of violence includes murder or attempted murder, bombing, arson, vandalism, trespassing, kidnapping, burglary, stalking, death threats, assault/battery, Butyric acid attacks and bioterrorism threats.