GWEN IFILL: 14 people are dead and another 17 wounded, including 10 critically, after the nation's latest mass shooting.

It happened in San Bernardino, a city of more than 200,000 people, about 60 miles east of Los Angeles.

Gunmen attacked a banquet facility at a social services complex, then fled. But authorities now say suspects died in a shootout with officers hours after the attack.

It was late morning when heavily armed police and others raced toward Inland Regional Center moments after the alarm sounded.

WOMAN: Apparently, the subject is still inside the business, 1365 South Waterman. It's in building number three, possible active shooter, male in black clothing. He's still firing rounds.

GWEN IFILL: The social services center is one of 21 that's run by the state, serving people with developmental disabilities.

JARROD BURGUAN, San Bernardino Police Chief: Preliminary information indicates that these are people that came prepared, that they were dressed and equipped in a way to indicate that they were prepared, and they had — they were armed with long guns, not handguns. They came prepared to do what they did as if they were on a mission.

GWEN IFILL: Marcos Aguilera said his wife was inside the building when the shooting started.

MARCOS AGUILERA, Family Member: She said the guy shot next — came in next to her office, and I guess started shooting. They locked themselves in, in her office.

They seen bodies on the floor. And she said, right now, ambulances are taking people out in stretchers.

GWEN IFILL: SWAT teams descended on the facility. And employees and others walked out with their hands in the air, while the wounded were wheeled away on gurneys and triage centers were set up on roadways nearby.

As the afternoon wore on, dozens of police flocked to nearby streets and joined the manhunt.

Hours later and dozens of miles away, they got into a gun battle with two people in a black SUV. One person lay motionless in the street and officers pulled another from the bullet-riddled vehicle.

JARROD BURGUAN: We had multiple officers that were involved in the shooting. We have two suspects that are dead at the scene. One is a male, one is a female. We had one police officer that was wounded. He has injuries that are not considered to be life-threatening and he as at a local hospital and is expected to be okay.

Meanwhile, President Obama says the San Bernardino assault reinforces yet again the need to prevent mass shootings.

PRESIDENT BARACK OBAMA: We should come together in a bipartisan basis at every level of government to make these rare, as opposed to normal. We should never think that this is something that just happens in the ordinary course of events, because it doesn't happen with the same frequency in other countries.

GWEN IFILL: The San Bernardino attack joins more than 350 shootings in the United States this year that killed four or more people.

Our producers caught up with a witness to the standoff with police a short time ago.

MAN: And once we got to like right there, they started shooting. We started hearing like cracks. And those officers were barely – not even with their vests buckled up, that's how quick they were trying to get out of the car. They were literally coming out of the car with their vests not even buckled in, like.

GWEN IFILL: Today's assault is the worst since December 2012. We'll have more up on that right after the news summary.

GWEN IFILL: But first we get the latest on that mass shooting from San Bernardino. Our own Hari Sreenivasan is now on the scene.

Hari, there are so many loose ends that we have heard, and one of them seems to be that the local FBI folks on the ground will not rule out terrorism.

HARI SREENIVASAN: That's right. At the most recent press conference, the FBI said that they can't rule it out. They can't rule it in. But at this point they said that they will go where the investigation leads them, and that could be domestic terrorism. That could be something more. But right now they just don't know enough about exactly who these people were, what their motives were, behind this attack today.

GWEN IFILL: Another loose end, Hari, seemed to be that they are still looking, examining and searching the building where this all took place. What are they looking for?

HARI SREENIVASAN: Well, right now they are looking for any clues as to what these people left behind, was there anything else? Was there any sort of an explosive device? That was one of the concerns earlier this afternoon, and in fact there was even an object next to the SUV where the shootout occurred, and they had to spend quite some time making sure that that wasn't an explosive, that wasn't a pipe bomb. But that was one of the concerns that they had.

So considering that these two individuals who are dressed in full tactical gear, considering what they were able to carry out today, they're very concerned on perhaps if this place is booby-trapped, perhaps if there are other things that could be big problems for authorities.

GWEN IFILL: You talk about the two, the ones that we heard about, the man and the woman who were found in tactical gear who were killed by police. But there's apparently still at least a third suspect on the loose?

HARI SREENIVASAN: Well, the third individual was seen running from the SUV, that particular area, and at the most recent press conference, they said, look, we have detained this person, we still don't actually know whether or not they're connected or how – if they are connected, how so. So this could've been somebody fleeing for a completely different reason, but right now the authorities have that person in custody and they're trying to figure out if there's a connection between that third individual. And perhaps if there's a fourth or a fifth, if there's something else, if there's a larger plot at play.

GWEN IFILL: So as far as we know, the one thing we know for sure is that this investigation, which started at this center for disabilities, has now extended to nearby towns and cities.

HARI SREENIVASAN: You know, yes. And one of the things that you notice here, I mean, this is a – San Bernardino is a city of 200,000 people and just getting to this location this afternoon, it is eerily quiet. We're talking strip malls are shut down, road closures. I mean there are certain parts of town that are of course running as normal, but really this is a place where even in these areas that were cordoned off, people are trying to get home or people are perhaps stuck inside the area and trying to reach their loved ones on the outside. So this is significant disruption for this small a place.

GWEN IFILL: And a virtual shutdown in many respects in some parts of the town.

HARI SREENIVASAN: Yes, that's right.

GWEN IFILL: Okay, Hari, you stay safe and keep us up to date. Thank you very much.