Due to a Security Alert, this train will not be stopping at Birmingham International

No explanation was given. Our train had stopped just short of the station before the announcement was made. When we got to New Street, I noticed that the next train to International had been cancelled. There was also an announcement saying that the next train to London Euston (which normally stops at International) would not be stopping there.

I don't know what happened there - I hope it was nothing serious, just something like accidentally unattended luggage.

Update: 09:15
The National Rail Enquiries web site has the following announcement: Train services on all routes via Birmingham International are being disrupted due to a security alert. Birmingham International is currently evacuated and train services are currently unable to call at this station

Update: 10:20
Found this:

BIRMINGHAM International train station has been evacuated this morning following reports of a suspect package.

British Transport Police ordered the station's operator Virgin Trains to close the building at 8.48am.
No trains are stopping at the station, although they are still able to pass through.

A spokesperson for British Transport Police said: "We can confirm that Birmingham International railway station is currently evacuated.

"Officers are at the scene following reports of a suspicious item and a person is helping us with our enquiries.

"Trains are continuing to operate through the station."

There was also news about this on the BBC website.