CNN  — 

A day after Thanksgiving, two civilians and a police officer were killed when a gunman opened fire – leading to a nearly six hour standoff – at a Colorado Planned Parenthood clinic. Police arrested the suspected gunman, but the motive for the shooting was not immediately known.

Fear, horror, disbelief among witnesses of Planned Parenthood shooting

Presidential candidates took to Twitter to share condolences for the community, with Democratic candidates Hillary Clinton, Bernie Sanders and Martin O’Malley publicizing their support for the nonprofit organization.

Obama on Colorado Planned Parenthood shooting: ‘Enough is enough’