An apparently berserk young Russian, wildly swinging an ax in a crowd of Swedish tourists outside the prestigious Intourist Hotel here yesterday, killed two elderly persons and seriously injured a third.

The attack occurred shortly after noon as the Swedish tourists were heading for lunch in the hotel on busy Gorky Street, a block from the Kremlin.

Eyewitnesses said the man waded into the group from behind, and began swinging at random. Three persons fell before Soviet police and chauffeurs standing nearby subdued the attacker and dragged him into the hotel.

The dead, all Swedish, were identified by Soviet sources as Annar Andersen, 83, and Eve Helen Johannensen, 67. The injured person was identified as Johannensen's husband, Henry, 71.

Soviet sources identified the attacker as Alexander Nazhinsky, 24, a Moscow night watchman. One source told a Western reporter that Nazhinsky was "schizophrenic."

Tass, the official Soviet news agency, described the attacker as "a mentally deranged person."

"The criminal was detained by the militia and an investigation is under way," Tass said.

United Press International quoted militia officials as saying that Nazhinsky had said, "I felt like killing someone today."

Eyewitnesses described Nazhinsky as tall and muscular, weighing about 220 pounds.

Tourists from several countries, including the United States, saw the attack or its aftermath. The Intourist Hotel is used almost exclusively for foreigners. One of the quests there now is Christina Onassis, daughter of the late Greek shipping magnate, Aristotle Onassis.

Eyewitnesses said Johannesen, although injured, had attempted to aid his wife, and then collapsed. He was taken to a hospital in serious condition, with bandages on his head witnesses said. Tass indicated that one of the two other victims was alive on arrival at a hospital but died later.

Tass said that an official of Intourist, the Soviet state tourist agency, had "expressed condolences to the Swedish Embassy" for the "tragic incident."

Such an attack is extremely rare in the Soviet Union but just last month, a few blacks from the Intourist, a man later identified as an escaped criminal took two hostages in the office of the Finnish national airline and fought a gunbattle with police before being forced out by tear gas.