At least 21 people have been killed in a bomb blast in a market in northern Pakistan.<br /><br /> Some 40 others were wounded in the explosion in the remote Kurram region, which borders Afghanistan.<br /><br /> The Pakistani army says helicopters were being provided to transport the wounded to hospital.<br /><br /> Some reports spoke about a suicide bomber, others say the blast was caused by a homemade device.<br /><br /> Taliban militants have previously been active in the area but there has also been tension between Shiite and Sunni Muslims.<br />
