Nearly four years after the terrorist attacks on the World Trade Center, the Fire Department released recordings Friday of radio traffic from September 11, 2001, as well as interviews from the surviving firefighters.

The material includes hours of audio and thousands of pages of transcripts, providing direct, first-hand accounts of the day.

"We just had a plane crash into an upper floor of the World Trade Center ‹ transmit a second alarm and start relocating companies into the area," one firefighter says at the start of the recording made of the FDNY's Manhattan dispatcher.

"We have a number of floors on fire. It looks like the plane was aiming towards the building," says another firefighter at one point.

In a later recording, a firefighter is heard running up the stairway of the north tower as people are coming down.

In addition to the radio recordings, the oral histories provide varying accounts of the day's events. In one of histories, a firefighter recalls that he heard a call, one minute after the first plane crash, to evacuate while he was on the north tower's 35th floor.

"My radio came clear as day, 'Imminent collapse. This was a terrorist attack. Evacuate.' That's exactly what I heard," says Firefighter Paul Bessler in the interview.

Yet another says his FDNY radio was barely functioning that day.

Another interview provides a clue as to the confusion that firefighters felt while they were inside the towers.

"We really didn't hear much on our radios," says firefighter Craig Dunne. "One of the Port Authority police, I believe they said they heard a possible collapse, possible terrorist activity. I didn't know the building came down until we got outside."

The materials are being made public due to a lawsuit filed by the New York Times and the families of the victims. The Fire Department had fought to keep the recordings and documents private, but a judge ordered the release.

While the federal September 11th Commission used the information to detail flaws in the city's response to the attacks, families of fallen firefighters have said that they want to hear the conversations for themselves.

The audio recordings were released in a 23-CD set that included transmissions from both EMS and FDNY units, covering the time-frame from about 8:45 a.m. to 1:30 p.m. on September 11. The FDNY recordings included audio from both the Manhattan and Brooklyn dispatchers.

Many families of firefighters and emergency workers that died in the WTC attacks say listening to the descriptions of the chaos given by firefighters confirm their feelings that the emergency communication systems failed their loved ones on September 11th.

Most also say the release of these documents is just a partial victory.

"We have the right to know what happened in the World Trade Center," said Sally Regenhard, who lost her son in the attacks. "Nine-eleven has been sanitized."

"We have to understand what happened that day so that we can do better in the future. I owe that to my son," says Al Regenhard, Sally's husband.

"I say to you Mr. Mayor and Mr. Pataki, and everybody that's involved in this: this will not go away. We will find out the truth. If I die tomorrow, my family will pick up this quest," said Rosemary Cain, whose son died on 9/11.

The FDNY conducted the interviews with the surviving firefighters shortly after 9/11.

In a statement, the Fire Department says it believes the tapes will "further confirm the bravery and courage of our members who responded to the World Trade Center. It is the department's hope that the release of these records will not cause our members and their families any additional pain or anguish."

Mayor Michael Bloomberg spoke out against the tapes' release on Friday. On his weekly radio show, the mayor said the conversations should have remained private.

"The city did not think that we should release them. There's all sorts of privacy issues," said Bloomberg. "People said things when they called 911, or the firefighters and police officers talking to each other, that probably would be best for everybody if it just was not released."