Three Arab terrorists, armed with machine pistols, and a high-ranking French police officer were killed yesterday when Israeli security agents foiled an attack on passengers waiting for an El Al flight at Paris' Orly Airport.

Eyewitnesses said that at least two of the terrorists were killed by Israeli security guards after they tried to shoot their way into the departure area where a charter group of 200 French tourists were about to board a flight to Israel.

Three other French policemen were wounded along with three of the French passengers. All were reported to be in good condition.

The circumstances suggest that the terrorists were planning a suicide mission along the lines of the 1972 Lod Airport terrorist killings in which 28 persons were gunned down in Israel by Japanese terrorists.

The dimensions of the potential disaster at Orly became evident when hand grenades and plastic explosives were found by the bodies of the gunmen.

French officials said that the identity papers the terrorists carried appeared to be false. Apparently based on airline tickets found on the bodies, an official said the men had arrived at Orly earlier in the day from Tunis. He said they carried a Lebanese, a Kuwaiti and a Tunisian passport. Those who examined the bodies closely said they were "definitely Middle Eastern types." They were said to appear to be no older than 25.

According to an unofficial but authoritative eyewitness account, yesterday's episode took Place as follow:

Israeli security agents at Orly spotted a group of five men spending a suspiciously long time mingling with passengers boarding an Iberia airlines flight for Malaga, Spain, across the corridor from the entrance to Gate 30, where the charter group was to board El Al Flight 324. The plan was scheduled to take off at 4:20 p.m. Paris time.

At about 3:40 p.m., one of the five men tried to go through the door to the El Al waiting room but an Israeli airline employe blocked his passage and asked him where he wanted to fly.

The man replied he was going to Zagreb in Yugoslavia. The El Al man told him he was at the wrong gate.

Then the man, who was carrying a soft handbag, returned to two of his companions, who also had hand luggage. One of the three gesticulated to the other two. All three opened their handbags.

Out came three Beretta machine pistols. They shot off a burst at the French police guards at the gate.

Passengers, Israeli security men and El Al employes and police all hurriedly obeyed cries of "get down, get down."

Firing from the floor, the Israelis felled two of the gunmen. The third managed to retreat some distance before dying from French police or Israeli bullets or both.

The other two men, who had seemed to be with the group of three that opene fire, did not take part in the shooting. They vanished in the general confusion without anyone being able to establish whether they really part of the terrorist operation.

The Israeli security men, who appeared visibly shaken when seen less than an hour after the shooting, were given strict orders not to talk to the Press.

El Al President Mordechai Hod said in a radio interview from Tel Aviv that the Israel security men helped the French police kill the attackers.

"The terroriists," he said, "did not have any chance to fire more than one burst before the French policemen and our security agents returned the fire."

Interior Minister Christian Bonnet said that the shootout started after "El Al agents" signaled the pressence of five suspicious looking persons to the police.

A Frenchman who was one of the charter passengers gave this account of the shooting:

"I heard firecrackers. Really, I thought it was fireworks. And I saw a policeman who was searching us take out his pistol and hit the dirt.

"I didn't react to get down, and I saw a guy a little like in the movies who had a machine gun and who started to shoot, but really . . . he was shooting very slowly - rat-tat-tat, rat-tat-tat, rat-tat-a, and the guy was dressed in brown, in Khaki.

"Finally, I saw one of my colleagues fall. He was hit in the face, full of blood . . . I plunged to the floor. We saw two riot policemen who were apparently wounded and we were told to get on our bellies. And we were told, 'Go out, go out.' So we all got out."

The Orly terminal was closed to the public for more than two hours after the shooting while hundreds of French police searched for other possible terrorists. During that period, conflicting rumors about the shootout flew all over the airport and were broadcast over French radio stations. Dozens of of riot police, Paris city police and plainclothesmen stood or crouched by all of the terminal exits with arms at the ready as the search continued.

At one point French police burst into a locked toilet in their search of the airport.

According to prefect Jean Perier, who provided the official police version of the incident, "We suspected that two more terrorists were hiding in a toilet, but police officers forced their way in with tear gas and found no one inside."

All the while, the bodies of two of the terrorists, sprawled on the floor could be seen over an internal television screen in the airport press room. The bodies remained untouched until the bomb squad arrived to remove the hand grenades and plastice explosives that had spilled out of their hand luggage in the fusillade. The third terrorist, who had fled into an airport security search compartment, collapsed there and died of his wounds.

Police denied rumors that spread around the airport of a second shooting.

The dead policeman, whose identity was withheld pending notification of next of kin, was a chief brigadier in the riot police. He was said to be one year from retirement.

El Al President Hod said that his company would conduct an investigation into security conditions at Orly. Although he said his first impression was that security measures there are "very good," observers maintain that the airport's main security weakness has for a long time been the fact that arriving passengers may mingle with departing ones.

Passengers coming from most other airports have presumably been subjected to careful security searches before embarking, but security at some Arab or other Third World airports is sometimes lax.

The charter group, madeup by the French insurance company L'Abeille (The Bee), was postponed and may be canceled.

Yesterday's attack was the fourth terrorist action against El Al at Orly Airport in six years.

Israeli Ambassador to France Mordechai Gazit and Israeli Labor Minister Israel Katz were at the airport at the time, but neither witnessed the shooting.ting.