Oval station in Kennington, south London, was one of those evacuated after Thursday's minor explosions.
The normally busy area around Oval station was sealed off
Reports say passengers and others tried to stop a man who made off when the train doors opened, but he escaped into a nearby park.
Businesses, shops and homes in the area were evacuated for more than eight hours and surrounding roads were closed for much of the day.
Overnight armed police officers guarded the entrance to the station.
Police confirmed few details of the incident, saying only an attempt was made to set off an explosive device.
But one BBC correspondent was told that a suspect on a train used a handgun to try to detonate explosives in a rucksack.
A Tube passenger said there was something on her train's floor and she "could see something had exploded".
The Northern Line passenger, who gave her name only as Andrea, told the BBC she had heard a bang, and saw a man running away.
"It sounded like a balloon had popped but a lot louder and then we all moved to one end of the carriage.
"There was something on the floor and you could see something had exploded.
"They opened the door so we could move through to the next carriage and there was a guy still standing in the carriage.
"And then we pulled into Oval, we all got off on the platform and the guy just ran and started running up the escalator.
"Everyone was screaming for someone to stop him.
"He ran past me and I kind of stood in one of the alcoves and he ran out of the station. In fact, he left a bag on the train."
Ingrid Guion, who was also on the train, said: "I just saw all these people coming towards my carriage and there was a strong smell.
"I just thought it was a person, just with the smell, and that people wanted to run away from him.
"Then we stopped in Oval and were asked to leave, and then we just had this smell again and I nearly fainted because we couldn't breathe.
"Apparently a guy was running away so they tried to catch him. Some people saw him and they saw a small bomb explode in a bag, but it didn't hurt anybody, there was just loads and loads of smoke."
Another eyewitness also spoke of "champagne corks popping" and "acrid smoke", and another of someone running from the station.
The blast was on the Northern line of the London Underground
Another said he was in the ticket hall when he heard screaming and an argument coming from the platform.
A man then came running out, being chased. As he ran he was reportedly shouting, "what's wrong with these people?".
The witness said he heard no explosion.
Dean Duffy said he had just left the station when he heard a bang.
"I saw people coming out, some were running, some were walking, some were telling other people to calm down and not to panic," he said.
The station was evacuated and residents who were out told not to return home
"I went straight back, sprinted back and one of the train staff stopped me, said 'don't worry, you know, people are on the way'.
"The police turned up within minutes, it seemed like seconds really."
As the train pulled into Oval, a man fled up the escalator, leaving a bag behind.