Horrified and scared, Mr. Fidrya did the one factor he might assume to do: He held on tight to the toilet door, which didn’t lock, attempting to guard the group in case the assailants got here to seek out them.

“Whereas we might hear capturing and screaming, I stood the entire time holding the toilet door shut,” Mr. Fidrya, a tutorial, mentioned in a cellphone interview from Moscow. “The others have been standing within the nook in order that if somebody began capturing by means of the door, they wouldn’t be within the line of fireplace.”

They didn’t understand it then, however they have been sheltering from what turned Russia’s deadliest terror assault in twenty years, after 4 gunmen had entered the favored live performance venue and commenced capturing rapid-fire weapons.

Their story is certainly one of many harrowing accounts which have emerged within the days because the assault, which killed no less than 137 individuals. Greater than 100 injured persons are hospitalized, some in important situation, well being officers mentioned.

Mr. Fidrya’s small group waited and waited, however the attackers had began a fireplace within the advanced and it was spreading. Mr. Fidrya’s spouse, Olga, confirmed everybody how you can moist their T-shirts and maintain them to their faces so they might breathe with out inhaling poisonous smoke.

After which a second spherical of pictures rang out.

After about half an hour, it was so smoky that Mr. Fidrya, 42, thought even the assailants should have left. As he ventured out, he noticed the physique of a useless girl mendacity by the escalator. Later he noticed the physique of one other girl who had been killed within the carnage, her distraught husband standing over her.

His group went down into the parking storage and ultimately emerged on the road because the emergency service staff have been carrying victims from the constructing.

The Islamic State, by means of its information company, claimed duty for the assault. U.S. officers mentioned the assailants have been believed to be a part of ISIS-Ok, an Islamic State affiliate in Afghanistan. On Saturday, Russia’s Federal Safety Providers introduced that 11 individuals had been detained, together with 4 who have been arrested after the automotive they have been fleeing in was intercepted by authorities 230 miles southwest of Moscow.

In interviews, survivors described how what began as a typical Friday night time out devolved right into a scene of panic and terror. The venue, which seated 6,200 individuals, had been bought out for a present by a veteran Russian band known as Piknik.

Video footage from the scene reveals the assailants capturing on the entrance to the live performance venue, a part of a sprawling, upscale advanced of buildings that additionally features a shopping center and a number of exhibition halls. They then moved into the live performance corridor, the place they sprayed gunfire as properly, movies present.

The attackers additionally set the constructing on fireplace utilizing a mixture of explosives and flammable liquid, Russian authorities mentioned.

Just like the Fidryas, Tatyana Farafontova initially thought the sound of the capturing was a part of the present.

“5 minutes earlier than the present was supposed to start out, we heard these boring claps,” she wrote on her VK social media web page. Ms. Farafontova, 38, mentioned in a direct message on Saturday that she was nonetheless in shock and was slurring her speech after the assault.

Then the claps acquired nearer and somebody shouted that there have been attackers capturing. She scrambled onto the stage with the help of her husband.

“For the time being after we climbed onto the stage, three individuals entered the corridor with machine weapons,” she wrote in her VK account. “They shot at the whole lot that moved. My husband from the stage noticed bluish smoke filling the corridor.”

Ms. Farafontova mentioned that being on the middle of the stage made her really feel uncovered and focused.

“It felt as in the event that they have been poking me within the again with the muzzle of a machine gun,” she wrote, including, “I might really feel the breath of loss of life proper behind my shoulders.”

She crawled below the curtain and ultimately adopted the musicians, who had already began to flee, and ran so far as she might from the constructing.

Up on the balcony, Aleksandr Pyankov and his spouse, Anna, heard the gunshots and lay on the ground for a while earlier than becoming a member of others who jumped up and commenced operating to the exit.

As they fled, they encountered a lady who had slumped down on an escalator and was blocking their route. She was alive however staring blankly forward, Mr. Pyankov, a publishing govt, mentioned. He informed her to maintain operating, however then turned his head and noticed what she was looking at.

“I began to look,” Mr. Pyankov, 51, mentioned in a phone interview. “And first I noticed a murdered girl sitting on the couch, and there was a younger man mendacity subsequent to her. I regarded round and there have been teams of our bodies.”

All of it occurred in a matter of seconds, he mentioned, and he tried to maintain fleeing.

“The worst factor is that on this scenario you’re not operating away from the capturing, however towards it,” he mentioned. “As a result of it was already clear that there could be a fireplace there, we all know how it will burn. And also you’re simply operating to determine the place else to run.”

Anastasiya Volkova misplaced each her mother and father within the assault. She informed 5 TV, a state channel, that she had missed a name from her mom on Friday night time at across the time of the assault. When she known as again, there was no response, Ms. Volkova mentioned.

“I couldn’t reply the cellphone. I didn’t hear the decision,” Ms. Volkova informed the broadcaster, including that her mom had been “actually wanting ahead to this live performance.”

Accounts rising about others who died within the assault additionally informed tales of keen concertgoers who had made particular efforts to get to the present.

Irina Okisheva and her husband, Pavel Okishev, traveled lots of of miles — making their method from Kirov, northeast of Moscow. Mr. Okishev had obtained the tickets as an early birthday current, the newspaper Komsomolsaya Pravda reported. He didn’t dwell to have fun his thirty fifth birthday, which is that this week. Each he and his spouse died within the assault.

And Alexander Baklemyshev, 51, had lengthy dreamed about seeing Piknik, a heritage rock band that was enjoying the primary of two sold-out live shows accompanied by a symphony orchestra.

Mr. Baklemyshev’s son informed native media that his father had traveled solo from his hometown of Satka, some 1,000 miles east of Moscow, for the live performance.

His son, Maksim, informed the Russian information outlet MSK1 that his father had despatched him a video of the live performance corridor earlier than the assault. That was the final he had heard from him.

“There was no final dialog,” his son mentioned. “All that was left is the video, and nothing extra.”

Mr. Fidrya mentioned he felt grateful to be alive, and that 4 of the assailants had been captured.

“Now there’s confidence that the crime will probably be solved and people non-humans who organized and carried it out will probably be punished,” he mentioned. “This actually helps loads.”

However photos of the victims stay seared in his reminiscence, particularly that of the husband, his again burned from the fireplace, standing over his useless spouse exterior the constructing as medics attended to the wounded.

The person was speaking to Mr. Fidrya’s spouse, Olga, saying they have been from the town of Tver northwest of Moscow, had been collectively for 12 years and had three kids.

“For us it’s throughout, by and huge,” Mr. Fidrya wrote in a message after the cellphone interview. “However for that man who stood over the physique of his spouse, and for his or her three kids, the worst is but to come back. And there are such a lot of individuals like him there.”

Oleg Matsnev contributed reporting.