Foreign journalists, including this correspondent, were at Langson in northeast Vietnam, 13 miles from the Chinese border, when the Sino-Vietnamese war broke out Saturday.

When we arrived Friday night, life in the town appeared normal. Children were playing badminton in the street and the only reminder of the nearby frontier was the presence of several soldiers and militiamen.

But at 5 a.m. Saturday the town was awakened by heavy gunfire from the frontier.

Half an hour later the barrage intensified and continued almost uninterrupted for 20 minutes.

It was difficult to get a clear idea of the situation on the ground since Vietnamese officials barred us from leaving the town because of "the intensity of the Chinese bombardment." By 8:30 a.m. the gunfire seemed to be nearer.

At 9 a.m. the whistle of a mortar shell could be heard distinctly momests before it exploded near the town, and 10 minutes later unidentified fighter planes flew high overhead, apparently from the direction of Vietnam toward the frontier.

At 9:45 a.m. a senior provincial official said, "Chinese troops have launched a general attack against the province. All the frontier posts have been shelled by heavy artillery."

The official continued: "Bloody fighting is taking place. Several posts held by militia and by frontier guards have been encircled."

By 11:30 a.m. cannon fire reverberated with increasing frequency, with explosions every 10 to 30 seconds.

Wounded began arriving at Langson hospital and the chief doctor said: "They come from Dongdang," a few miles from the frontier.

The gunfire increased again at about 12:30 p.m. but eased 30 minutes later, and at 2:30 p.m. we were authorized to head for the frontier.

On the road we passed several groups of civilians carrying bundles as they fled the combat zone, but there were no vehicles.

The sound of shellfire and automatic weapons grew steadily clearer, and after six miles we left the road for a mountain path.

After rejoining the road about a mile farther on we were stopped by a group of Vietnamese troops. Their leader, Pham Ngoc Hong, said: "We were encircled in our position. We got out across the fields."

"The Chinese regulars are about half a mile from here. There are a lot of them."

A young Vietnamese soldier appeared around a bend in the road 100 yards away, staggered and fell. Van Mien, 18, had been hit in his right shoulder by a shell fragment.

"The Chinese are close by. They are everywhere," he said.

The crackle of approaching automatic gunfire and urging of panicstricken Vietnamese with us persuaded us to withdraw, throwing ourselves to the ground everytime a shell landed nearby.

It seemed to us that the war had begun.