The South Korean government today denied reports that President Park Chung Hee was killed by enemies in an attempted coup, but the official version of his slaying left several unanswered questions.

The government maintained that the 61-year-old ruler was slain Friday by one man -- the head of the Korean Central Intelligence Agency -- in a dining room when a quarrel broke out. At least four and possible five other men were shot to death.

In the aftermath of the mysterious shooting, South Korea's armed forces were placed on alert against possible moves by Communist North Korea, and KCLA director Kim Jae Kyu was formally relieved of his post, government officials said today. Kim was arrested after the shooting and is being questioned by a martial law body set up today, a government spokesman said.

The main unanswered question centered on how the KCIA director could have managed alone to fire at least seven shots to kill Park, his chief of security, and either three or four other bodyguards and escape unharmed to authorities, as the government version maintains.

There was speculation that others may have been involved, but no evidence was made public to support that suspicion.

A presidential spokesman, Lim Bang Hyun, denied a foreign press report that Park was a coup victim.

"That's not true," he told reporters here. He said further details would be announced by the Cabinet as soon as martial law authorities have completed an investigation.

Meanwhile, Seoul remained calm today as it began a nine-day period of mourning for the man who ruled the country for 18 years with a stern hand and a policy of jailing dissenters.

Almost the entire country was under martial law with universities closed and all unauthorized meetings banned.

People shopped in downtown Seoul as on any Saturday afternoon, however. Many clustered around newspaper billboards to read the latest reports issues by the government.

Troops were stationed in government buildings and other key offices, and soldiers stood guard with automatic rifles at Seoul's Kimpo Airport.

Prime Minister Chol Kyu Huh, who was named acting president as the constitution provides, took command of the government.

The United States officially expressed sorrow for Park's death, promising to defend South Korea if the Communist North attacked. U.S. sources said there was no sign of unusual military activity across the Demilitarized Zone where the Communists are believed to have about 650,000 to 700,000 soldiers under arms.

As far as outsiders could determine the South Korean military was not seeking a share of power. About one division of men, including tanks and armored personnel carriers, was scattered around the city to enforce martial law commands. However, the troops were not deployed in the streets until this morning, about 12 hours after the shooting.

The defense minister and four top uniformed officers promised to support the civilian leadership, and observers here said they had seen no sign of military complicity in any plot.

The government said, in its only official explanation that Park was killed by the KCIA's Kim in an "accident" that grew out of an argument between Kim and Park's cheif of security, Cha Ji Chul.

The official version said Kim shot Cha, accidentally hitting and fatally wounding Park, and then gunned down four other bodyguards who rushed to the president's defense in a dining room at a KCLA executive command post near the Blue House, the presidental residence. At least three and possibly all four of the bodyguards were slain.

In this version, Kim was the only person present who was not in Park's official entourage. According to the account, Kim would have had to have fired at least seven shots in quick succession. Two of the shots, it was reported, struck Park -- one in the head and one in the chest.

Park was rushed to the hospital, according to other sources, by his personal secretary, Kim Kye Won, who was also in the dinning room and was the only one, except the KCIA chief, to survive. The shooting occurred at 7:30 p.m. Friday, and Park was pronounced dead at 7:50 p.m., the government said.

According to reports coming either directly or indirectly from the government, Park had been invited by Kim of the KCIA, a loyal supporter, and they sat down to dinner about 6 p.m. with Park's security chief and the personal secretary.

There has been no explanation of what started the argument that the government said led to the shooting. One version being circulated widely asserts that Kim and Cha were old enemies who differed angrily over the government's handling of recent troubles, including defiant statements by opposition leader Kim Young Sam and student riots that struck two southern cities.

According to this account, the KCLA's Kim had taken a soft line, advocating a moderate approach to avoid a widening struggle, Cha, it was said, was a hard-liner who wanted student demonstrations crushed and Kim Young Sam curbed.

That version fit with the general perception here of the two men. Kim was considered a moderate when he was appointed KCLA director three years ago. A former Army lieutenant general, he had been a childhood friend of President Park.

Cha, also a close friend of President Park, was a former general who participated in the 1961 military coup that brought Park to power.

The official version also failed to answer this question: How did the KCIA's Kim apparently manage to slip away from the scene of the shooting without being stopped? He was said to have surrendered voluntarily to military authorities later. It was not known how long he was at large after the shooting.

This and the large number of shots fired raised suspicions here that other persons may have been involved. But no evidence was immediately available to support that suspicion.

There was also nothing to indicate why Park was dining at the KCLA offices. However, local observers said it was not common for him to eat there with friends. He had returned from a visit to the countryside earlier in the day.

The American response was quick and supportive of the government. In a letter to Acting President Choi, President Carter expressed a "deep sense of shock and sorrow." He said Park had been a "firm friend" of the United States would stand firmly behind its treaty commitment to South Korea.

About 35,000 American troops are stationed in South Korea. U.S. sources said that their alert status had been stepped up by "one notch," but that no extraordinary precaution had been ordered.

Park is to be buried Nov. 3 at the National Cemetery on a hillside overlooking Seoul. His wife, who was slain during an assassination attemp on Park in 1974, is buried there.

Acting President Choi will serve until new elections are held to choose a successor to complete the five years of Park's unexpired term. It will not be a direct election. The successor will be chosen by the 2,800-member National Council of Unification, which was elected last year by the public for the specific purpose of voting for a president. Park won easily last year.

Observers here predict a lengthy jockeying for position among Park's loyalists who will seek the presidency. Choi is not likely to try for the job. A career bureaucrat and former foreign minister, he was wielded little power in his role of prime minister.