Initial reports said witnesses heard a plane going overhead shortly before the first explosions - but police were quick to dismiss that suggestion, insisting the incident was an "accident".
Security sources say the threat from Islamic terrorists is as great as ever it was. At least five suspected terror cells are being monitored by police and MI5. The cells are said to be at various stages of planning independent attacks here and abroad.
http://www.timesonline.co.uk/article/0,,2087-1869844,00.html