DHAHRAN, SAUDI ARABIA, JAN. 22 -- It was about 7:15 here this morning, after the second Iraqi Scud missile alert in three hours, when Cable News Network correspondent Charles Jaco lost it. Reporting live from the roof of the Dhahran International Hotel, Jaco heard a boom and thought he smelled something odd. "I felt dizzy, I couldn't breathe and my lips went numb -- all in the space of about a half a second," Jaco said.

"Gas!" Jaco shouted on the air, and then donned his gas mask.

With that mistaken report of an Iraqi poison gas attack, Jaco briefly scared the wits out of millions of CNN viewers. But nowhere was the fear greater than here in this eastern Saudi Arabian city where more than 500 reporters, photographers, network cameramen, producers and technicians have assembled to cover the war -- only to spend much of their time filing in and out of bomb shelters. And while many veteran foreign correspondents went about their work as routinely as possible, others were shaken by the frequent alerts.

"When I saw Jaco clap the gas mask on his face, my heart stopped," said Peter Copeland, a Pentagon reporter for Scripps-Howard News Service who was watching Jaco's broadcast from a nearby hotel. "I thought this was it."

Six days into the Persian Gulf war, some of the correspondents here are getting jumpy. Many have never been close to a battlefield before. The incessant air raid sirens and missile alerts of the past few nights are taking their toll, causing reporters to lose sleep, miss deadlines and, every so often, when they are advised by hotel security to put on their gas masks and chemical suits, fear for their lives.

"People are tired, they're edgy and they're getting pissed off that this is continuing," said a bleary-eyed Stewart Powell, a veteran military reporter who is here covering the war for Hearst Newspapers.

"The whole thing makes me mad -- like who are you to shoot missiles at me," said Julie Bird, a reporter for Army Times. "It makes me mad that no one in this country can go anyplace without a gas mask, that every time I go to bed, I don't know whether in the middle of the night there's going to be another launch."

The tensions have been greatest at the Dhahran International, a five-star hotel that has become the command center for international media coverage of the war. All four U.S. networks have set up sophisticated studios on the roof. The hotel is also headquarters for the controversial Joint Information Bureau (JIB). That is the Pentagon unit set up to oversee media pool coverage of the war and to ensure that reporters don't give away details about allied military plans. To do so, JIB officials review all stories filed by pool reporters, an arrangement that has infuriated some news organizations. ("We don't censor anybody, we security-review people," Army Lt. Col. Larry Icenogle, the director of JIB pool coverage, tells reporters who protest the procedure.)

Not surprisingly, security at the Dhahran International is every bit as rigorous as Icenogle's vetters. U.S. soldiers wielding M16s stand guard in front, checking the credentials of all who enter the hotel lobby. Hotel management has hired a former British Royal Air Force specialist in chemical and biological warfare, Philip S.M. Congdon, as a consultant charged with protecting the hotel's employees and guests from Saddam's arsenal.

Congdon, who finds it "appalling" that the Pentagon and many news organizations haven't equipped reporters with chemical suits and anti-nerve gas agents, has become a ubiquitous presence at the hotel. Each evening, when the sirens sound, Congdon throws on his gas mask and issues orders through a megaphone, directing the hordes of journalists as they trudge down the stairwells to the bomb shelters in the basement.

Many reporters praise Congdon for his calm demeanor and efficient instructions. But sometimes they say he is a bit too matter-of-fact. During the first Scud attack last week, Congdon at one point calmly informed the assembled reporters that they "may wish to put on" their full chemical protection suits should they happen to have one. Most don't.

During that attack, "you could see beads of perspiration pouring down people's brows," said New York Times reporter Philip Shenon.

Another reason for the edginess is that with the exception of reporting on the Scud attacks, there is not that much for many reporters to do here. Access to U.S. or other allied military officials is strictly limited to designated members of the JIB-controlled pools.

As a result, reporters who are not members of one of the pools can offer their home offices little more than rewrites of the pool reports. "This is sort of like covering the White House with air raid drills," said Craigg Hines, Washington bureau chief of the Houston Chronicle. "You read pool reports, you watch CNN, and you write your story."

Most of the news organizations set up their headquarters in Dhahran because it is the closest major city to the front, some 200 miles from the Kuwaiti border. But all news briefings are handled at the Joint Allied Command Headquarters in the Saudi capital of Riyadh or at the Pentagon. Queries to the JIB about the war generally produce polite suggestions to contact Pentagon officials elsewhere. "There is no information here," fumed ABC correspondent Sam Donaldson as he stood in front of the Joint Information Bureau sign. "You can't even ask them what the weather was like in Iraq today. Peter Jennings will want to talk to me about what I know about the oil well fires in Kuwait and I have to say, 'Peter, I don't know a thing.' "