(CNN) Smoke everywhere. People jumping out of rail-car windows. Crawling, bleeding, covered in blood.

Metro passengers described the aftermath of the subway blast in St. Petersburg, Russia on Monday as scenes of horror.

Stanislav Listyev told CNN: "I was going down the escalator at Sennaya Square at about 2:30 p.m. -- and at that moment I felt an explosion wave underneath, everything filled with smoke, people started panicking.

"So the trains stopped and almost immediately the evacuation started. I think that explosion happened in the tunnel between the stations. The smoke was coming out of there. There was nothing on the station itself, everything was fine."

'They were bleeding out'

Alexey Chirochkin was sitting on a bench in the subway station with his earphones on when he noticed a woman approaching him, he said. As he got up to give her his seat, the woman fell and he grabbed her.

Her face and hands were bloody, and she started crying when he asked if she needed an ambulance, he said.

"Then I take my earphones off, I look around (and I see that) the station is full of smoke," Chirochkin said. "People are running, panic (takes over). But there was no crowd. (People) did not jump over each other, did not push each other ... Some were jumping out of (the metro car's) windows."

"I saw a lot of injured people," he said. "People were crawling while bleeding. They had such a look in their eyes. A girl was yelling, 'Please help my guy!'"

Subway employees ordered people to leave the scene, he said.

Chirochkin recalled helping a man pry open the jammed, bent train doors to pull a victim out of a car and lay him on the platform.

"It is possible that a person that I dragged out was dead," Chirochkin said. "He had a lot of blood on his jacket."

The scene inside the train cars horrified him.

"People there did not have whole bodies ... They were not asking for help. They were not moving," Chirochkin said. "Their eyes were glassy. They were bleeding out."

An unnamed eyewitness who spoke to the state news agency, Tass, said: "In the metro car, everyone expected death, if I can say that."

Photos: Explosion on St. Petersburg train The damaged door of a train car is seen after an explosion on the subway in St. Petersburg, Russia, on Monday, April 3. Multiple people were killed in the blast. Hide Caption 1 of 11 Photos: Explosion on St. Petersburg train Smoke fills a subway station near the blast. The explosion, which authorities described as a terrorist attack, took place on a subway car as the train was in a tunnel between the Sennaya Ploshchad and Tekhnologichesky Institut stations. Hide Caption 2 of 11 Photos: Explosion on St. Petersburg train The damaged train car is seen at the Tekhnologichesky Institut station in St. Petersburg. Dozens were reported injured in the blast. Hide Caption 3 of 11 Photos: Explosion on St. Petersburg train The aftermath of the explosion is evident at the Tekhnologichesky Institut subway station. Hide Caption 4 of 11 Photos: Explosion on St. Petersburg train A person is rushed away from the scene on a stretcher. Hide Caption 5 of 11 Photos: Explosion on St. Petersburg train A woman makes a phone call at the entrance to the Tekhnologichesky Institut station. Hide Caption 6 of 11 Photos: Explosion on St. Petersburg train Emergency workers are seen outside the entrance to the Tekhnologichesky Institut station. Hide Caption 7 of 11 Photos: Explosion on St. Petersburg train A man with bleeding hands stands outside the entrance to the Tekhnologichesky Institut station. Hide Caption 8 of 11 Photos: Explosion on St. Petersburg train An emergency-response helicopter takes off near the Tekhnologichesky Institut station. Hide Caption 9 of 11 Photos: Explosion on St. Petersburg train Firefighters and ambulances respond at the Sennaya Ploshchad station. Hide Caption 10 of 11 Photos: Explosion on St. Petersburg train Police in the city take extra security measures after the explosion. Hide Caption 11 of 11

"After the explosion, everyone expected consequences, then we were taken out, and people began to help each other, brought others out, most were covered in blood."

'I saw dead people'

Another witness told Tass that people waited for evacuation for several minutes after the explosion, which took place between the Sennaya Ploshchad and Tekhnologichesky Institute stations in central St. Petersburg.

"I saw dead people, three (or) four people minimum, the emergency services arrived after five (to) seven minutes," he said.

A woman interviewed by Life News in Russia said: "The people were bloody, they had their hair burned. Smoke came out of the cars. We were told to move to the exit, because the traffic was stopped. People just ran.

"My friend was in a metro car near to the one which exploded. She said it shook. When she came out, she saw that people were all disfigured."

'Many were crying'

St. Petersburg resident Leonid Chaika, who said he was at the station where the blast happened, told Reuters: "I saw a lot of smoke, a crowd making its way to the escalators, people with blood and other people's insides on their clothes, bloody faces. Many were crying."

JUST WATCHED Bystanders rush to rescue trapped passengers Replay More Videos ... MUST WATCH Bystanders rush to rescue trapped passengers 01:04

Geoff Edwards, 68, from Liverpool, England, works in St. Petersburg. He told the BBC he is a quarter of a mile away from the scene.

"There are helicopters flying around right now, I can hear them out of the window," he said. "A colleague told me that one landed near the station -- to collect dead bodies. "

Meanwhile Instagram user @a_shevala posted a video of emergency responders at Sennaya Square in the aftermath.

Вертолёт на Сенной A post shared by Антон Шевела (@a_shevela) on Apr 3, 2017 at 5:48am PDT

And Instagram user @kuchynskaya shared a video of ambulances rushing to the scene and then racing away to the hospital.

На Загородном проспекте звук сирены скорой не прекращается. Машины ездят как в сторону Технологического института, так и в сторону Мариинской больницы. Ужас ужас #метро#спб#взрыв#теракт#петербург A post shared by Таня Кучинская (@kuchynskaya) on Apr 3, 2017 at 5:23am PDT

At least 10 people are reported dead, according to three state-run Russian news agencies. The death toll is one lower than the tally given by the Russian Health Ministry earlier in the day. At least three dozen are injured, the Health Ministry said. Other agencies in St. Petersburg gave differing numbers for the injured.