US President Barack Obama has renewed his call for tighter gun control following a deadly shooting at a family planning clinic in Colorado Springs, Colorado.
Mr Obama, whose gun control efforts have been opposed in congress, said: "We can't let it become normal."
Two civilians and a police officer died and nine other people were injured in the five-hour standoff at the Planned Parenthood clinic.
The suspected gunman, Robert Lewis Dear, was arrested.
He has been described as a loner who lived in a mountain cabin in North Carolina.
Police did not give details on the gun used but in a statement Mr Obama described it as "an assault weapon".
"This is not normal," he said.
"We can't let it become normal.
"If we truly care about this - if we are going to offer up our thoughts and prayers again, for God knows how many times, with a truly clean conscience - then we have to do something about the easy accessibility of weapons of war on our streets to people who have no business wielding them. Enough is enough."
Mr Obama has previously said that his failure to pass "common sense gun safety laws" in the US was the greatest frustration of his presidency.
Officials have not speculated on a possible motive for the attack but Colorado Springs Mayor John Suthers said people could make "inferences from where it took place".
The Planned Parenthood group - the largest single provider of abortion in the US - has drawn anti-abortion protests in the past.
Dear apparently said "no more baby parts" while he was being arrested, NBC News and other media reported on Saturday, citing unnamed law enforcement sources.
The utterance would appear to be a reference to the controversy surrounding the organisation's services, and its role in delivering fetal tissue to medical researchers.
On Saturday (local time), city police tweeted that they were searching a property linked to the suspect in the town of Hartsel, 105 kilometres west of where the shooting took place.
"If you talked to him, nothing with him was very cognitive - topics all over the place,'' said James Russell, who lives near the shack.
The dead police officer was named as Garrett Swasey, 44, who was married with two children.
Originally from Massachusetts, Mr Swasey moved to Colorado to pursue a career as a figure skater, and competed in national championships.
"He was a great dad," his father David told the Boston Globe. "Everybody in the police department loved him. Anybody who ever met him loved him."
The other two victims have not yet been named.
Colorado Springs Police Chief Peter Carey said five police officers were among the injured, who were being treated in local hospitals.
In a statement, Planned Parenthood said it was not yet clear "if Planned Parenthood was in fact the target of this attack".
The organisation has been the focus of protests recently after an anti-abortion organisation secretly recorded one of its staff discussing how to obtain aborted foetal tissue for medical research.
Pro-life advocates said this proved Planned Parenthood was selling foetal parts for profit - which is illegal - but this was disputed by the organisation.