The suspect who carried out a deadly gun attack on a family planning clinic in Colorado told police officers "no more baby parts" soon after his arrest. Police are exploring the motive behind Robert Lewis Dear's attack on the Planned Parenthood office, where three people were killed and nine others injured.

Multiple US news outlets reported that investigators confirmed Dear's comments, which he made shortly after he turned himself in to the authorities following a five-hour siege. The suspect's remarks are likely to flare up the rhetoric surrounding abortion.

Law enforcement officials hinted that Dear may have been impelled by strong anti-abortion views. NBC News, which first reported the comments, claimed that police officers said Dear had made several other remarks including some against President Barack Obama.

This is not the first time Planned Parenthood has come under attack. Its buildings were vandalised earlier after an anti-abortion group released a video in July 2015, allegedly showing the clinic's personnel negotiating the sale of fetal organs and parts for profit. Planned Parenthood disputed the authenticity of the video.

Vicki Cowart, president and CEO of Planned Parenthood Rocky Mountains has released a statement censuring the incident: "Today, we are learning that eyewitnesses confirm that the man who will be charged with the tragic and senseless shooting that resulted in the deaths of three people and injuries to nine others at Planned Parenthood's health centre in Colorado Springs was motivated by opposition to safe and legal abortion."

Dear, 57, opened fire on the clinic in Colorado Springs, which is located about 115km from Denver, and took some hostages. Subsequent to the five-hour siege, he surrendered. One police officer identified as 44-year-old Garrett Swasey, was among the three killed. The other two victims are yet to be named. The suspect is being held without bail in Colorado Springs jail.

Police are grilling people who know Dear to investigate the motive behind the attack. Dear's belongings including his computer are also being examined.

US Attorney General Loretta Lynch has condemned the attack. In a statement, Lynch said: "This unconscionable attack was not only a crime against the Colorado Springs community, but a crime against women receiving healthcare services at Planned Parenthood, law enforcement seeking to protect and serve, and other innocent people."