An e-cigarette is believed to have caused a small explosion at London Euston station, police said.
The station was closed for about 90 minutes while British Transport Police (BTP) investigated. London Underground trains did not stop at the station.
No-one was injured in the explosion, which was reported at 19:40 BST.
Network Rail advised there would be major disruption until the end of the day. It urged passengers to go to other stations to get to their destinations.