Good evening. Diane is on assignment tonight. And we do begin here with breaking news. We are learning just moments ago of an attack in afghanistan. Two u.S. Marines have been killed. We don't know if... See More
Good evening. Diane is on assignment tonight. And we do begin here with breaking news. We are learning just moments ago of an attack in afghanistan. Two u.S. Marines have been killed. We don't know if it is related to the same anti-american protests raging in the region but it comes on a day when america witnessed a somber co homecoming. Sean smith, glen dougherty, tyrone woods and u.S. Ambassador chris stevens. Their kas gets met by their grieving family and president obama. We'll have more on what the president and the secretary of state said to the families and to the nation in just a moment. But first, back to the latest on the afghanistan attacks we're learning of. Martha raddatz in washington tonight. Martha, what do we know? Reporter: This is what we know right now. It was a big attack on camp bastian in southern afghanistan. This is a base divided between a british side and an american side and it was a complex attack, involving many militants. As you said, two marines killed, three or four wounded and two harrier air draft damaged. The attack was carried out with rockets and small arms fire. It is apparently coming under control now, though, david. And martha, as we said at the top of the broadcast, we don't know if this is related to the unrest in the other part of that region. But we learned late this is the same base where prince harry is serving? Reporter: It is. But on the other side, we believe, where the attack occurred. And we don't know whether this had anything to do with that anti-muslim film. All we know at this hour, two u.S. Marines have been killed. We'll have more on this throughout the evening. We spent the afternoon reporting on that very somber homecoming for the four americans killed in libya. Reporter: We certainly did, david. As you said, there hasn't been an ambassador killed in a violent attack in over 30 years. It was ambassador chris stevens' flag-draped casket that was first brought off the cargo plane. U.S. Marines making the sad, solemn walk to the hanger where the families, the secretary, the president waited to honor all of the dead. Four americans, four patriots. They loved this country. And they choo serve it and served it well. They knew the danger and they accepted it. They didn't simply embrace the american ideal, they lived it, Reporter: For secretary clinton, it was personal. I was honored to know ambassador chris stevens. Chris won friends for the united states in far-flung places. He made those people's hopes his own. During the revolution in libya, he risked his life to help protect the libyan people from a tirnt. Reporter: She spoke of all those lost when the benghazi consulate was attacked by armed militants. Sean smith, the technology specialist, who leaved two young children behind. Tyrone woods, a former navy s.E.A.L., The father of three little boys. And his fellow former s.E.A.L., glen doherty, a beloved son and brother. We've seen rage and violence directed at american embassies over an awful internet video that we had nothing to do with. It is hard for the american people to makes sense of that because it is senseless. Reporter: But the message of today was not just of grief. It was resolve. So, we will wipe away our tears, stiffen our spines and face the future undaunted. Reporter: Indeed, the state department is in crisis mode, sending additional security to embassies around the world. David? Martha, thank you.
This transcript has been automatically generated and may not be 100% accurate.