BEIJING, June 4 - Bloody Sunday in Tiananmen Square will be remembered by Chinese at home and abroad as one of the darkest days in China’s history, one which is likely to blacken the names of several Chinese leaders for decades to come.

Here in the symbolic heart of China's capital, surrounded by its many monuments, 25-ton tanks of the People's Liberation Army were the main weapons of terror. Converging from east and west, they lined the northern side of the square, flattened the statue students had erected to honor democracy, and then ripped into the students' tent city encampment.

Tanks pursued student victims with machine guns, ran over some and smashed others like insects against walls.

Behind the tanks came soldiers and riot police, who beat students with truncheons and fired on them with automatic weapons.

Four Chinese witnesses who survived this bloody massacre said that the number of dead came to more than 700.

As troops moved through the city, clashing with protesters, a government announcement at 4 a.m. today in the square said there was a "counterrevolutionary rebellion in Tiananmen."

"The people have attacked the army and burned vehicles," the announcement said. "The troops will control Tiananmen Square. Leave now. The army has the right to use all means necessary to clear the square. Anyone not obeying the order must accept responsibility."

Four Chinese witnesses, all of whom asked not to be identified, said that at this point, the government turned the lights off in the 100-acre square, where thousands of students had encamped for three weeks to demand democratic reforms, including freedom of speech and the press, as well as official recognition of their democracy movement.

By the time the government decided to send the army against the demonstrators, the students' numbers had dwindled drastically. But a few thousand had stayed on, and many of them paid with their lives.

According to one witness, interviewed later today in Beijing, the army entered the square at 5:05 a.m. Some of the troops crawled into the square as though facing armed resistance, although there was none.

According to the witness, the students still in the square did not know what to expect. They had heard reports that some of the soldiers were using rubber bullets.

The witness, a 20-year-old university student, said several hundred students stood together in concentric circles around the statue honoring democracy that demonstrators had erected on the north side of Tiananmen Square. Before they faced the advancing army, the students said: "Immortality will give us democracy," and "We're not afraid to give our young blood for the future of the republic."

Many of these students were killed moments later when machine guns mounted on tanks that were massed on the north side of Tiananmen Square opened fire. Soldiers riding on the tanks mowed down some students with automatic weapons.

Tanks then flattened the statue and ripped into the student encampment located around it in the northern part of the square, crushing to death students huddled inside tents. The tanks rotated over their victims, the witness said.

The witness said he made his way to the southeast side of the square, crawling much of the way.

"Anybody who stood up was shot at," he said.

He described how four young women from Qinghua University held a soldier's legs and shouted: "We are all from the same family group. How can you do this to other Chinese?"

Soldiers bayoneted and killed one of the women and shot the others at close range, the witness said.

He said a male student held onto his girlfriend who had been shot in the back of the head by a soldier. The man could not let go; he was paralyzed, the witness said.

He said that near the Museum of Revolutionary History on the east side of the square, a woman with her 2- or 3-year-old son tried to run from the tanks. She and the boy were crushed, he said.

The witness said he crawled to the Chongwenmen area southeast of the square, passing bodies all along the way.

"Some people on the square wanted to die," he said. "Others couldn't move. . . . All who tried to run were killed. Those who were smart lay down and crawled."

"Tiananmen Square is full of red and bullet holes and people crying," the man said, once his escape was made.

"We never expected that soldiers would kill students like that," the witness said.

Three other witnesses, all researchers or graduate students, said that riot police armed with sticks and cattle prods followed the tanks into the square.

The witnesses said a soldier in plainclothes wearing a helmet and white shirt directed police, who cleared an "escape lane" for several hundred students who gathered around the Monument to the People's Heroes.

The lane became a passage of fire and death.

The police beat and prodded those who passed through. The witness said he heard several women students shout repeatedly as they ran, "I can't take it. I can't take it."

At the monument, where the student demonstrations began six weeks ago following the death of the late Communist Party chief Hu Yaobang, the students sang the socialist anthem "Internationale."

The witnesses estimated that about 300 died at the monument -- shot, beaten and trampled to death when they tried to escape.

When the students fled to the southeast of the square, most of them scattered to the east and west, a witness said.

Most moved to the west along the south side of the square and then north between the square and Great Hall of the People in an effort to reach the Xidan intersection to the west of Tiananmen.

On the way to Xidan, a student was cut in half by tank tracks, a witness said. Other students, seemingly senseless in the midst of the deadly chaos, picked up his torso and legs and carried them along.

At the Tongren hospital, a reporter for the China Times newspaper in Taiwan who stayed on the square with the students was given treatment for a wound at the back of the neck.

Between 5 a.m. and 6 a.m., about 5,000 students tried to run to Xidan, a witness said. He said a soldier firing a machine gun on a tank killed 20 of them, driving about 1,000 south toward the Beijing Concert Hall.

One tank crushed several students against the wall of the concert hall.

A woman standing 50 feet away from a soldier yelled, "Down with fascism," and the soldier shot her.

Anyone holding a banner became a target.

A soldier shot a worker who was helping the students by using his three-wheeled pedicab as a makeshift ambulance. Soldiers shot a man driving an ambulance loaded with the bodies of students.

"The citizens have no way to fight back," said a research student who insisted that soldiers burned bodies. The witness said there was no way to bring all the bodies away from Tiananmen Square and smoke seen rising from the square convinced him that this is what the soldiers did with the remains of the friends he left behind.

This witness said he then went home.

"Nobody can cry. Everybody is in shock," he said.

But despite the carnage in Tiananmen, he vowed that he would continue fighting the communist government and the leaders who ordered the army attack on Beijing.