Several fire and rescue services were dispatched to the scene with fans to blow the smoke out of the subway after someone released a smoke bomb on Sunday night.
The task only took the firemen a few minutes, and officials said that there was no risk the incident would affect traffic.
“Witnesses saw a couple of young men throw the bomb,” Mikael Ericson of the Stockholm police told TT. “The boys quickly ran from the scene.”
Ericson said that another individual almost managed to throw the smoke bomb out of the station, but it still filled the ticket hall with smoke, which then spread to the platforms.
“We haven’t arrested a suspect for this incident. A report for property damage has been filed.”
The platforms were deserted since the last train on the red line that runs through the station had already departed. There were no injuries.