london improvise explosive device explode pack rush-hour commuter train london injure 22 people friday police say fifth terrorism incident britain year know incident emergency service say call report fire train parsons green station west london 8.20 a.m. 0720 gmt train travel wimbledon south london toward city center morning commuter rush-hour report local media explosion people suffer facial burn 8.40 a.m. 10.15 a.m. police declare treat terrorism-related incident london ambulance service say take 18 people hospital follow incident witness say prompt stampede leave train none casualties suspect sustain serious injuries national health service say others take hospital bring total number treat 22. london fire brigade say six fire engines two fire rescue units 50 firefighters attendance british prime minister theresa may chair meet national security committee 1.00 pm 1200 gmt britain top counter-terrorism officer say blast result improvise explosive device picture share social media show embers burn white bucket wrap plastic shop bag wire protrude bucket witness describe acrid smell fill carriages former ministry defence head counter-terrorism tell sky news look pressure cooker device malfunction broadcaster also report device fully detonate metropolitan police counter terrorism unit lead investigation incident support british transport police mark rowley metropolitan police say intelligence service support police response detail information suspect might link blast rowley would draw whether attacker train time explosion much live investigation follow line enquiries rowley say comment ask idea know far london train bomb