A "small contained explosion" believed to have been caused by an e-cigarette in a bag forced London Euston station to be evacuated on Tuesday night.
The station was evacuated at around 7.40pm due to an "security alert".
There were reports that a "smoking package" had been found on one of the platforms.
British Transport Police said no one had been injured by the explosion.
The station had reopened by 9.10pm but Network Rail warned there would be "significant delays until the end of service".
Witnesses wrote on social media that people had been "running in panic" and "screaming" as the evacuation took place.
A British Transport Police spokesperson said officers and search dogs checked the station to make sure the area was safe before the station was reopened.
"There appears to have been a small contained explosion which is believed to have been caused by an e-cigarette which was in a bag at the station," the force said.
"No one is believed to have been injured."