Lt. Catherine Buckley, Colorado Springs Police:

COLORADO SPRINGS — (CNN) Police say they’re evacuating a Planned Parenthood building in Colorado Springs, Colorado, where a gunman has fired at officers.

“There are an unknown amount of casualties at this point,” Lt. Catherine Buckley told reporters around 4 p.m. (6 p.m. ET), adding that shots had been fired shortly before she spoke.

Even once gunfire stops, investigators will be at the scene for hours, she said, checking out items the gunman brought with him to make sure they aren’t explosives.

“We don’t know what they are,” she said. “We know that the suspect brought several items with him, and some of those are inside the Planned Parenthood building and some of them are out front of it.”

Officers exchanged gunfire with the suspect inside the building but were not in voice contact with him, she said.

At least four officers were injured in the shooting, she said. Local hospital officials said at least nine people were taken to medical facilities in the area. Details about their injuries were not immediately available

The shooting, which was first reported inside the building around 11:30 a.m. (1:30 p.m. ET), also left a nearby shopping center on lockdown as police searched for the gunman.

It’s unclear whether there are hostages or whether there’s an additional shooter involved, she said, and authorities have not identified the suspect.

FBI teams were among those responding to the scene, agency spokeswoman Deborah Sherman said.

It was not immediately clear whether Planned Parenthood was the target of the shooting.

Police said the original 911 call reporting the gunman came from the building.

One Planned Parenthood official said the motive behind the attack was unknown, but pointed to what she called a “poisonous environment that feeds domestic terrorism” as a possible cause.

“We don’t yet know the full circumstances and motives behind this criminal action, and we don’t yet know if Planned Parenthood was in fact the target of this attack,” Vicki Cowart, president and CEO of Planned Parenthood of the Rocky Mountains, said in a written statement. “We share the concerns of many Americans that extremists are creating a poisonous environment that feeds domestic terrorism in this country. We will never back away from providing care in a safe, supportive environment that millions of people rely on and trust.”

Witnesses: Police swarmed area

Denise Speller, who works at a nearby salon, said she heard at least 10 gunshots go off and saw a police officer get hit.

“It was terrifying,” she said, adding that it was unclear exactly where the shots were coming from.

Brigitte Wolfe, who said she works in the area of shooting, told CNN that she saw about five officers behind a building with their guns drawn, as well as about three SWAT vehicles and roughly seven police cars from her vantage point in a strip mall that’s across the street from the Planned Parenthood. A grocery store and bank are nearby, Wolfe noted.

Photos taken by Kody Fisher, a reporter with CNN affiliate KXRM, showed an ambulance and, in another photo, at least two police officers crouched behind a patrol car.

Colorado Springs police tweeted that the shooting took place on Centennial Boulevard. A newspaper in the city, The Gazette, reported that traffic was shut down in both directions on that road and that customers were told to stay put in a nearby grocery store and shops.

That sentiment was echoed by Colorado Springs police, who warned around 12:20 p.m. (2:20 p.m. ET) that the area was “not secure” that those in a nearby shopping center should “shelter in place.”

At a grocery store in the shopping center, an intercom announcement told shoppers not to leave.

The city, in the central part of the Colorado, has more than 400,000 residents.

Planned Parenthood: ‘This is a developing situation’

Hours after the shooting began, video from CNN affiliates showed people in medical scrubs and white coats being escorted from the scene.

Planned Parenthood is a national health care provider that delivers reproductive health care and sex education to women and men throughout the United States. The organization runs nearly 700 health centers throughout the United States, according to its website.

The group says each year 2.7 million people in the United States visit its health centers for health care services and information. Abortion is among the services Planned Parenthood clinics provide, an issue that’s made the organization a target in the past.

It’s faced sharp criticism in Washington and from some Republican presidential candidates on the campaign trail after an anti-abortion group released a series of videos alleging that Planned Parenthood engaged in the selling of fetal organs and parts for profit.

Planned Parenthood has strongly disputed the videos and contended the tapes provide a distorted account because they are heavily edited.

At least three Planned Parenthood buildings have been vandalized since September.

Last year, abortion providers in the United States saw 12 incidents of vandalism, one burglary, one invasion, one arson attack, one death threat and four stalking incidents, according to the National Abortion Federation.

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