Met police chief's full statement

Sir Ian Blair says casualty numbers appear to be very low

A number of Tube stations have been evacuated and lines closed after three blasts in what Metropolitan Police Commissioner Sir Ian Blair described as a "serious incident". Here is his full statement.

We know that we have four explosions, four attempts at explosions, and it's still pretty unclear as to what's happened.

There's certainly a scene at the Oval Underground station, there's a scene at Warren Street Underground station, there is a scene at Shepherd's Bush - which is on the Underground but is actually above ground - and there's a scene on a Number 26 bus at Hackney near Columbia Road, which I believe is in Bethnal Green.

At the moment the casualty numbers appear to be very low in the explosions.

The bombs appear to be smaller than on the last occasion.

I don't know the implications of all this yet. We have to examine the scene very carefully.

I have a couple of messages that I really need to give.

The first is the transport system is going to close down for a short while, while we work out what's happened.

The emergency services are getting control over a very confused scene. Clearly, this is a very serious incident

It's very important that Londoners and people in London stay where they are.

The second announcement is we will make a further announcement about what the travel implications are.

What we don't want is lots of people going to railway stations.

The trains, as far as I know, are still running.

It's just: 'Stay where you are, go about your normal business'.

Again, the plan is there, you've seen it happen before, it's rehearsed.

The emergency services are getting control over a very confused scene. Clearly, this is a very serious incident.

What I'm doing now is I'm going off to Cobra [the government emergency response committee] to meet the home secretary and others to see where we go from here.