As U.S. troops close in on Baghdad, they come across more and more of these suspicious sites, reports CBS News National Security Correspondent David Martin.
Tests at laboratories in the United States have to be completed before the presence of chemical weapons would be known, the officials said.
That's because it's not all that easy to tell the difference in the field between a chemical that can be used in a chemical weapon and a chemical that can be used as a pesticide, said Martin.
The 101st Airborne Division came upon one in an agricultural complex, where they found steel drums that were filled with liquid that tested positive for nerve agent, and for blister agent. And at the same time, some of the soldiers that were working in that area became sick, vomited, their skin broke out in splotches, so they were evacuated.
"This could be either some type of pesticide, because this was an agricultural compound," Gen. Benjamin Freakly said in a television interview. "On the other hand, it could be a chemical agent, not weaponized."
A Knight Ridder News Service journalist traveling with the unit said initial tests of samples from the facility were inconsistent. Some tests did not indicate chemical weapons, while others indicated the presence of G-class nerve agents — which include sarin and tabun — and mustard agent, a blistering chemical first used in World War I.
Defense Secretary Donald H. Rumsfeld acknowledged reports about the site Monday but said first reports often are incorrect.
"We have to take our time and look at it," Rumsfeld said, adding that getting samples back to the United States and completing testing can take days.
Sophisticated tests are needed to confirm the presence of chemical weapons because nerve agents are chemically very similar to many pesticides.
"Once it actually physically gets there, it doesn't take that long to actually run through the tests," said former U.N. weapons inspector and CBS News analyst Tim McCarthy. "So I think we should have a better idea in two or three days."
The Knight Ridder reporter, Tom Lasseter, also reported that he and several soldiers were decontaminated after some of the soldiers felt ill while searching the compound. Officials at the Pentagon said they did not have any information about anyone getting sick.
Freakly said that the soldiers were suffering from heat exhaustion, not chemical exposure, and all are doing fine. He said the soldiers were given showers to cool them down, not decontaminate them.
U.S. troops have been trained in what to do if they find suspected chemical and biological weapons caches.
"Probably more than any other soldiers in the world the U.S. military is prepared for this type of event," said McCarthy.
If the discovery was confirmed, it would be the first find of chemical weapons during the war. Finding and eliminating Saddam Hussein's chemical and biological weapons is a goal of the U.S.-led invasion of Iraq, and finding such weapons of mass destruction could mute international criticism of the war.
But one find may not be enough.
If the administration's story about what the Iraqis had in terms of weapons of mass destruction is going to stand up, there are going to have to be a lot of finds, not just one find in one location, said Martin.
Earlier reports about possible chemical weapons finds have turned out to be false alarms. Last week, for example, troops searching the Qaa Qaa military complex south of Baghdad found a white powder that was found to be an explosive.
Iraq acknowledged making 3,859 tons of sarin, tabun, mustard and other chemical weapons, though United Nations inspectors suspected Iraq could have made much more.
"Even if it was shown to be chemical agents, it would be a small part of the whole picture," McCarthy said on the CBS News Early Show.
Iraq used mustard and sarin against Iran during the 1980-88 Iran-Iraq war and is believed to have used the chemicals against Kurdish Iraqis.
Sarin and tabun are related nerve agents that can kill when absorbed through the skin or inhaled as a gas. They kill by causing convulsions, paralysis and asphyxiation.
Mustard agent begins dissolving tissues on contact and is particularly harmful to eyes and lungs. It does not usually kill but causes painful injuries that can linger for a lifetime.
If what the 101st Airborne found does turn out to be a chemical agent, "this is going to be the first of many finds," said McCarthy. "As we know from our inspections, the Iraqis hid things all over the country in sort of obscure places."
As an inspector, McCarthy didn't visit this site.
"And I even looked at the UNMOVIC, the more recent team, their inspections, and as far as I could tell, this particular site no one has been to," he said. "That's not unusual. There are many places like this all over Iraq."