Transcript for Libya Investigation Shows 'Complex Attack'
And now we have some breaking news to tell you about tonight, just as we came on the air, new details from the state department about what happened in libya, the violence that cost four americans their lives including u.S. Ambassador chris stevens and abc's jarl is standing by with this late news. Jon? Reporter: This is ahead of a major congressional hearing tomorrow into what happened in that attack on our consulate in libyament and we are hearing new details, details that we have never heard before about what went down and this is significantly different than what we were told at the time. At the time as you recall we were told it was a protest that went bad and became an attack. Now we are told there was no protest going on outside that embassy. The first indication that they heard anything outside the walls of the embassy, of the consulate compound was an explosion and gunfire. They looked through a camera to see what was going on and we are told they saw a large number of armed men coming in and approaching that compound. We're told it was a very complex attack without precedent in u.S. Diplomatic history, we've never seen an attack like this in libya or anywhere else we were told, by this senior state department official. So, diane, one other fascinating detail is they still don't know how ambassador stevens got to Doctors at the hospital took the cell phone out of his pant, out of his pocket and started calling it. That's how they found out that he was there. Jon, this is a incredible breaking news toght. So any explanation for the change in the story? Reporter: Well, this is a part of their investigation. They say they continue to investigate but they have never given us anywhere near a detailed time line like this and believe me a big part of this, diane, is because you have this major congressional hearing tomorrow and wanted to get this out now. All right, these new developments just in, thank you, jon karl.
This transcript has been automatically generated and may not be 100% accurate.