A high steel fence surrounds the U.S. military hospital here, but today it was those on the outside who seemed the prisoners.

While the day's traffic sped by on an adjacent highway, reporters and camera crews paced the sidewalk outside the hospital like caged animals. Periodically they pressed their faces against the bars, straining their eyes to catch sight of someone inside and then hurriedly consulting their cheat sheets of hostage photographs.

At least one of the former captives was recognizable to everybody. When hostage spokesman Allyn Conwell walked across the hospital yard to the gate leading outside, the pushing and shoving began.

"Allyn, Allyn," yelled NBC anchor Tom Brokaw from outside the fence, beckoning Conwell's attention toward a famous and familiar face.

Conwell just kept walking. Straight out the gate, across the sidewalk and into a waiting ABC limousine.

For the newspaper and radio correspondents gathered here from around the world it was a small satisfaction to see the American networks scooping one another after two days of jointly scooping the rest of the press corps.

From the Lear jets flown daily between Cyprus and Beirut to the hostage interview exclusives in Lebanon and the live reports from Damascus, Syria, it had been the same. The American networks had the money, the clout, the personnel and most of all the elbows to make the hostage drama their story.

By this evening, most of the hundreds of journalists here seemed to share the apparent wish of the hostages and their families that the reporters, along with the drama, all would just go away.

By now, following the arrival here of 52 hostages from Iran in 1981, and the wounded Marines flown here last year from the Beirut bombings, both the U.S. government and the press have developed a routine. Frankfurt International Airport, which shares a runway with the U.S. Rhein-Main air base, is well equipped to handle such crises. By Saturday morning, when it looked as if the hostages would be released that day, the airport's Sheraton Hotel, as well as most smaller hostelries in the area, was full of journalists. Most were from the United States but others came from virtually every western European country and some from as far away as Australia.

The Air Force had set up a press accreditation system, issuing passes to reporters to allow them to enter the base and witness the arrival of the hostages from Damascus. By midday Saturday, it had run out of accreditation forms.

By evening it was clear the hostages were not coming and attention turned to the hostages' families who were arriving to meet them. But reporters quickly found that many of the families had had their fill of media attention in their home towns. Hotel room doors were angrily slammed in the faces of inquiring reporters. Telephones, finally, were not answered.

Those who had success were primarily network reporters, whose organizations, at least in the cases of ABC and NBC, had bought first and sometimes exclusive rights to family and hostage stories for the price of an airplane ticket to Frankfurt and "protection" from journalistic competitors.

At the same time, the Reagan administration, ever conscious of the use of visuals, played its own part in shaping the coverage. When the hostages finally did land at dawn today, a press pool was allowed out on the runway, along with Vice President Bush and a group of dignitaries. The pool consisted of television cameramen and photographers only.

But everyone knew the real story was to be told by the released hostages themselves after they had had time to rest, be reunited with their families and undergo medical examinations. For this, the military had a plan. While the former captives were whisked into buses after landing and taken 25 miles to the hospital, reporters were told to submit written requests for interviews with individual ex-hostages.

Unlike in the Iranian situation, there would be no press conference organized for the Beirut 39. The written requests would be given them inside the hospital and those who wanted to respond could send messages to reporters standing outside the fence.

By 10 a.m. today, the hospital press office had received hundreds of letters and the reporters lined up to wait. At noon, hospital commander Col. Charles K. Maffet emerged to hold a briefing. The hostages, he said, were in good health. They had "firm handshakes" and no apparent psychological problems. Maffet acknowledged he had examined none of the hostages himself, and had only briefly greeted them three hours earlier.

Meanwhile, the sidewalk vigil had begun and just after 1 p.m. there was movement. The gates slid open and the pack rushed forward, only to be stopped by hefty Air Force guards, who said that only the networks -- requested by the hostage families they had "sponsored" -- were to be allowed inside.

Two print reporters sneaked in behind them, one by identifying himself as a CBS technician. The gates banged shut on the rest.

Inside, the networks had set up their equipment on the lawn, waiting to go live with hostage interviews on their respective morning news programs. There were technical hitches, and the several hostages and their families stood around glumly. Without the live connection home the reporters did not seem interested in talking to them.

Hostage Stuart Darsch of Boston sat with his girlfriend and waited to be noticed. Finally, just as the live hookup was made with NBC "Today" host Bryant Gumbel, lightning flashed and thunder shook the sky. As the rain began to pour, a television technician handed Darsch an umbrella and Gumbel, dry in New York, began to speak.

There were no more hostage interviews. Although groups of camera crews from each of the networks remained outside just in case, the day's news at the hospital was over.

At about 3 p.m. a military spokesman walked to the gate and faced the now drenched and hostile bulk of the press corps. Something, he acknowledged, had gone wrong. The American networks had the story but no one else did.

In the end, it was the hostages themselves who saved the day. By early evening, many had grown tired of their privileged positions inside the fence. Along with family members who had been permitted inside, they began to leave and head for hotels and restaurants around Frankfurt.

One by one, looking weary and resigned to their new status as media stars, they began to tell their stories to the reporters who had followed them.