DENVER (AP) _ In a chilling display of how the Oklahoma City bombing shattered a normal morning, prosecutors played an audiotape today that picked up the booming explosion followed by the sound of panicked screams.

Cynthia Lou Klaver, a state water board lawyer holding a meeting across the street from the downtown federal building, began taping at 9 a.m. on April 19, 1995. The meeting came to an abrupt halt two minutes later.

``Basically there are four elements I have to receive information regarding .....BOOM!''

Chairs can be heard falling and a voice yells, ``Everybody out of here now!'' Another person screams: ``What's going on? What's going on?''

And then Klaver yells: ``Let's get out of here!''

``I thought the whole building was coming down on us,'' she testified today. ``I didn't know if we were going to get out.''

``There was debris, lights, wires hanging all over. Everyone was very bewildered.''

Klaver said there was rubble at the front door, so they left by the back door.

``There were some people sitting on the curbs, cut up. It seemed very desolate and quiet, smoke everywhere,'' she said.

That afternoon, employees called each other to see who was still missing. One employee, Trudy Rigby, couldn't be found

``Did you ever see her alive again,'' U.S. Attorney Patrick Ryan asked.

``I did not,'' Klaver replied.

McVeigh attorney Stephen Jones did not ask her any questions.

The prosecution planned to spend the day calling other witnesses who could convey the sights and sounds of the worst terrorist attack on American soil, showing the jury horrified victims, falling ash, burning cars.

The second witness, Marine recruiter Michael Norfleet, arrived at the federal building and said he walked right by the parked Ryder rental truck _ about an arm's length away.

Once he reached the Marines' sixth-floor office, he greeted two supply sergeants.

``About the time I got hello and good morning out of my mouth, the bomb hit,'' he said. ``I was facing the front of the building, so I was facing glass.''

``All I remember is following the blood trail from somebody before me.''

Jones made his own attempt to grab the emotional spotlight Thursday, opening the defense case by solemnly reading the names of all 168 people who died in the blast. It was a tactic that brought some relatives in the courtroom to tears.

Jones said the government's case against McVeigh is based more on his political beliefs _ many of which are held by millions of other Americans _ than on hard evidence.

``If Tim McVeigh built the bomb and put it in the truck, our proof will be that his fingernails, his nostrils, his hair, his clothing, his car, his shoes, his socks would have it all over them. They don't,'' Jones said.

``Millions of innocent people fear and distrust the federal government and were outraged,'' he said. ``Being outraged is no more an excuse for blowing up a federal building than being against the government means that you did it.''

In his opening statement, Assistant U.S. Attorney Joseph Hartzler said McVeigh had a twisted plot to incite a second American revolution, fueled by revenge for what he saw as a government slaughter of innocents at the Branch Davidian compound near Waco, Texas, two years to the day before the bombing.

Papers found in McVeigh's car after he was arrested on traffic charges 90 minutes after the blast are a ``virtually a manifesto declaring McVeigh's intention,'' Hartzler said.

Among the papers were slips of statements quoting ``The Turner Diaries,'' a 1978 fictional account of an attack on a federal building that is eerily similar to the Oklahoma City bombing.

The prosecutor said that on the day of the bombing McVeigh was wearing a T-shirt that bore the Thomas Jefferson quote: ``The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants.''

``McVeigh liked to consider himself a patriot,'' Hartzler said. ``Our forefathers did not fight innocent women and children. ... They didn't plant bombs and run away wearing earplugs.''

In a new revelation, Hartzler said federal agents found a file in a computer belonging to McVeigh's sister marked ``ATF READ.''

``You'll see the chilling words, `All you tyrannical m----- f------ will swing in the wind some day for your treasonous actions against the Constitution. ... Die, you spineless, cowardice bastards.''

Jones told jurors to listen to the government's case and remember one thing: ``Every pancake has two sides.''

His presentation offered none of the elaborate theories of international conspiracy that he had floated before the trial. Instead, he spent most of two hours focusing on what he said were the shortcomings of the government's evidence and the contradictions among witnesses.

Jones lashed out at scientists with the beleaguered FBI lab for practicing ``forensic prostitution'' by slanting scientific work in favor of the prosecution.

Hartzler acknowledged the problems at the FBI crime lab, but said, ``None of the people who have been criticized for their work at the FBI lab will be witnesses in this case.''