Q&A on the history of attacks against Planned Parenthood

The attack comes as the nonprofit endures criticism from anti-abortion lawmakers and renewed protests outside clinics since a group of abortion opponents released videos they claimed showed the organization negotiating fetal tissue sales.

WHAT VIOLENCE HAVE ABORTION CLINICS OR PROVIDERS FACED?

Since 1977, there have been eight murders, 17 attempted murders, 42 bombings, 186 arsons and thousands of other incidents, including vandalism, according to the National Abortion Foundation, a trade group for abortion providers.

The campaign against Planned Parenthood has intensified since July, when anti-abortion activists who posed as representatives of a biomedical firm began releasing a series of undercover videos.

Planned Parenthood said that video and the others were misleading and deceptively edited.

Since the videos began airing, threats against abortion clinics nationwide have spiked, said Vicki Saporta, president and CEO of the National Abortion Federation.

Cowart dismissed the suggestion of installing metal detectors at the clinic, saying: "Nobody deserves to walk through a metal detector to access health care."