Mission which circled saturn for 13 years, sending back never before seen images. Good evening and welcome to bbc news. An explosion on a tube train in south west london this morning is being treated as a terrorist attack. Witnesses have spoken of a flash and a bang and then panic as commuters ran out of the carriage. 29 people have been treated in hospital, some suffering from burns. The incident happened in the morning rush hour as a District Line tube train pulled into the overground station at Parsons Green in south west london at 8. 20am. The bbc understands that the bomb, described as a homemade device, had been fitted with a timer, but it failed to fully detonate. Whoever planted it is still on the run. Tom symonds has our first report tonight. At 8. 20am, the friday commute was well under way. A packed commuter train, young, old, children, pensioners, everyone. At Parsons Green station, where the lines run overground, a brief stop. I stepped on and within two seconds, a massive