A suicide bomb blast in the centre of Istanbul has injured 22 people, including 10 policemen, according to BBC News. Police say the bomber tried to board a police bus in Taksim Square. Twelve civilians were also hurt. No group has said it carried out the attack, but a two-month-old ceasefire by Kurdish rebels was due to expire later on Sunday. Police identified other bombs nearby and have been working to disable them. Television pictures from Taksim Square showed body parts lying on the ground. A large explosion was heard throughout central Istanbul just after 0900 GMT. The explosion took place right next to the independence monument on Taksim Square, which is always crowded with people. There are usually squads of riot police posted at this part of the square, as it is often the site of demonstrations. A police spokesman has said he believes they were the target of the explosion, which he said may have been caused by a suicide bomber. Eyewitness Aris Virkas told the BBC that he was walking through Taksim Square when he heard the blast.