COLORADO SPRINGS, Colo. -- A man from North Carolina described as a loner who avoided eye contact opened fire at a Colorado Planned Parenthood clinic and killed three people, including a police officer, authorities and neighbors said.

Authorities weren't ready to discuss a possible motive Saturday after interviewing 57-year-old suspect Robert Lewis Dear, Colorado Springs Mayor John Suthers said.

However, people can make "inferences from where it took place," said Suthers, a former state attorney general who also suggested Dear's mental health was part of the investigation.

Those who knew Dear said he seemed to have few religious or political leanings.

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"If you talked to him, nothing with him was very cognitive - topics all over place," said James Russell, who lives a few hundred feet from Dear in the North Carolina town of Black Mountain. A cross made of twigs hung Saturday on the wall of Dear's pale yellow shack.

Dear's cabin is a half-mile up a curvy dirt road about 15 miles west of Asheville, North Carolina. He also had a trailer in the nearby town of Swannanoa.

Robert Lewis Dear, 57, of North Carolina is seen in a booking photo released by the Colorado Springs Police Department.

Other neighbors knew Dear but didn't want to give their names because they said they were fearful he might retaliate.

Russell and others said the only companion they saw with Dear was a mangy dog that looked to be in such bad shape they called animal control because they worried he was beating it.

Late Saturday, authorities said Dear listed his residency in Hartsel, Colorado.

Police say Dear entered the Planned Parenthood clinic in Colorado Springs and opened fire on Friday. The five-hour siege that followed included several gun battles with police as patients and staff members took cover under furniture and inside locked rooms.

By the time the shooter surrendered, three people were dead - including a police officer - and nine others were wounded.

Sources told CBS News that Dear surrendered Friday after realizing that he was cornered and had nowhere to run, CBS News correspondent David Begnaud reports. Since then, he's been cooperating with investigators.

Law enforcement sources said police were able to tap into the Planned Parenthood building's surveillance camera system, CBS News justice correspondent Jeff Pegues reports. Near the end of the standoff, they were able to pinpoint where the gunman was in the building.

It marked the latest mass shooting to stun the nation and prompted President Obama to warn, "We can't let it become normal."

"If we're 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," the president said.

Planned Parenthood said all its staff members at the clinic were safe and that it did not know whether the organization was the target of the attack.

University of Colorado police officer Garrett Swasey UCCS

University of Colorado police officer Garrett Swasey, 44, a six-year veteran of the force, was killed during the siege. He was married and had a son and daughter, according to the website of his church, Hope Chapel in Colorado Springs.

No details were immediately available about the two civilians who died. Five other officers and four people were hospitalized in good condition. At least four of those victims were later released.

"Certainly it could have been much, much worse if it were not for the heroism of our police officers to corner the person in the building," Colorado Springs Fire Chief Chris Riley said.

Suthers praised the security staff on duty at the clinic and said they were helpful in working with police to monitor the gunman's whereabouts on surveillance video and advising on the building's layout.

Witnesses described a chaotic scene when the shooting first started just before noon.

Ozy Licano said he was in the parking lot of the two-story building and trying to escape in his car when the gunman looked at him.

"He came out, and we looked each other in the eye, and he started aiming, and then he started shooting," Licano said. "I saw two holes go right through my windshield as I was trying to quickly back up and he just kept shooting and I started bleeding."

Licano drove away and took refuge at a nearby grocery store.

"He was aiming for my head," Licano said of the gunman. "It's just weird to stare in the face of someone like that. And he didn't win."

Inside the clinic, Jennifer Motolinia ducked under a table and called her brother, Joan, to leave him final instructions for the care of her three children in case the gunman found her.

Joan Motolinia said he could hear gunshots in the background as his sister spoke. "She was telling me to take care of her babies because she could get killed," he said.

For others, the first sign that something was wrong came when police appeared and ushered people to the second floor. Planned Parenthood employee Cynthia Garcia told her mother, Tina Garcia, that the officers wouldn't say why they were gathering everybody together. Then she heard the gunshots.

Her daughter and the others were holed up for hours while the standoff raged, Tina Garcia said.

Some people managed to escape the building and flee to a nearby bank. An armored vehicle was seen taking evacuees away from the clinic to ambulances waiting nearby.

For hours, police had no communication with the shooter other than hearing his intermittent gunfire from inside the Colorado Springs clinic. Officers eventually moved in, shouted at the gunman and persuaded him to surrender, police said.

About five hours after the attack started, authorities led away a man wearing a white T-shirt.

A suspect, identified as Robert Lewis Dear of North Carolina, is taken into custody outside a Planned Parenthood center in Colorado Springs, Colorado, Nov. 27, 2015. Reuters

With the immediate threat over, authorities swept the building and turned their attention to inspecting unspecified items the gunman left outside the building or carried inside in bags. They were concerned that he had planted improvised explosive devices meant to cause even more destruction.

Police Lt. Catherine Buckley said Saturday the items were no longer a threat. She declined to elaborate.