Pravda said Monday residents thought war had broken out when a freight train packed with 120 tons of explosives blew up at a rail crossing in a city near Gorky, killing at least 68 people and injuring 230.

"First I saw a high column of flames shoot up. Then I heard a rumbling, and then a great mushroom cloud rose," the official Communist Party daily quoted a witness, V. Dormidontov, as saying.Soviet news reports said Saturday's blast in Arzamas, an industrial city about 240 miles east of Moscow, flattened several city blocks and tossed railroad cars and other vehicles like feathers.

Dozens of doctors were rushed to the city, and rescue workers continued Monday to go through the debris. Pravda said the true death toll may never be known. In some areas, all that was left from the blast were car wheels or rubble from multistory apartment buildings, Monday's paper added.

Soviet media said the blast involved three boxcars packed with industrial explosives and destroyed the homes of 600 people. At least eight children were among those killed.

The official media's reporting of the disaster was among its most detailed and rapid ever about such an accident - an apparent sign of Mikhail S. Gorbachev's policy of "glasnost," or greater openness.

What shocked Arzamas residents, Pravda said "was not the damaged houses or destroyed cars but the crippled people calling for help."

The newspaper quoted one unidentified, weeping woman as saying: "The first thing that came to my mind was, has it started?" an apparent reference to war.

Witnesses said the explosion was so powerful that windows were shattered about 11/2 miles away and sections of track were discovered a mile from the accident site, the news reports said.

Pravda described the scene as being one of "brief panic," but said those who were not injured quickly rushed to help victims.

More than 80 doctors were flown to Arzamas, a city of more than 90,000 people. Nearby residents rushed to offer blood and food for the survivors, the media said.

Pravda said the death toll would probably mount: "How is it possible to determine how many people were killed in cars parked nearby?"

It noted that, in some cases, only wheels were left at the site. The story appeared on the back page of Monday's paper. There were no photographs.

A government commission was appointed to investigate the accident.

The three boxcars carried industrial explosives intended for geologists, mineworkers and builders, Tass said Sunday. The diesel locomotive pulling the cars flipped over in the blast, the daily Izvestia noted in its Sunday editions.

Cars and trucks halted near the track, waiting for the train to pass, "were scattered about as though they were feathers," Izvestia said.

Accidents were never reported in such detail before Gorbachev came to power in March 1985, but media stories of incidents have become more common and specific, especially since the Chernobyl nuclear accident in April 1986.