Several people have taken to Twitter to say they have been evacuated from the busy London Underground transport hub.
One person tweeted: “Just being evacuated from Westminster Station. Anyone know what’s going on?
“Another person wrote: “What’s happening at #Westminster station? Been evacuated.”
But the Metropolitan Police has now tweeted on its @MetPoliceEvents account the station has been closed due to a fire alarm.
The police wrote: “#Westminster Underground is currently closed due to a fire alarm.
“This is unrelated to the #ClimateStrike event but may impact those trying to join or leave the event.”
The London Fire Brigade (LFB) said they are at the scene to carry out an investigation.
The LFB tweeted: “Firefighters are investigating a fire alert at #Westminster underground station. More soon.”
A person in Westminster station at the time of the evacuation praised staff for their repaid response to the situation.
They told MyLondon: “We’re absolutely fine, grabbed emergency exit and were out of the station within less than a minute.
“The announcement just said ‘Due to a reported emergency, would all customers please leave the station’ if I remember correctly.
Another person caught up in the emergency tweeted the evacuation was due to a “small fire”.
The closure of the station comes as hundreds of people join in climate protests throughout the country, including around Parliament Square in Westminster.
Protests are taking place in a number of major cities, such as Cardiff, Glasgow, Sheffield, Nottingham, Bristol, Durham.
This is a breaking story. More to follow.