The news is saying the controlled explosion was on a bus.
Police evacuate Birmingham centre
Police used loud speakers to evacuate Birmingham's Broad Street
Police in Birmingham are evacuating large parts of the city centre amid a security alert.
West Midlands Police said people were being asked to leave the centre, particularly Broad Street, as a "precautionary measure".
No vehicles are being allowed past the inner ring road into the city centre, and there have also been reports of controlled explosions by police.
Police said it was in response to intelligence the force had received.
"It's quite tense," said BBC journalist Toby Brown.
No vehicles are being allowed to be moved, he added.
Birmingham resident Kenneth Kelsall told the BBC: "There is a lot of confusion, there appears to be no chance of anyone moving back into the city - but people are remaining quiet."
West Midlands Police announced they had received intelligence of a possible threat to the area around 2015BST.
Initially people were told to be on their guard and that bars and restaurants were being searched. Motorists were also told not to come into the city centre.
Around 2100BST the police announced that the city was to be evacuated.
http://news.bbc.co.uk/1/hi/uk/4668313.stm