Several hurt in 'terror' incident on London underground train

* Witness reports seeing flames in carriage* Police say called to incident at 8.20 am (local time)* Police treating it as terrorism incidentSeveral people were injured at a London underground station on Friday after witnesses reported a blast on a packed rush-hour commuter train which police were treating as a terrorism incident.Emergency services said they had been called to reports of a fire on a train at Parsons Green station in West London at 8.20 am (local time)."It is too early to confirm the cause of the fire, which will be subject to the investigation that is now underway by the Met's Counter Terrorism Command," London police said in a statement.Commissioner Neil Basu, the senior national coordinator for counter-terrorism policing, had declared it a terrorist incident, the statement said.The Metro newspaper reported that passengers had suffered facial burns from a blast and others had been hurt in a subsequent stampede.An unverified picture circulating on social media showed a white bucket with a supermarket freezer bag on the floor of one train carriage. The bucket was in flames and there appeared to be wires coming out of the top.Members of the emergency services work outside Parsons Green underground tube station in west London on Friday."I was on second carriage from the back. I just heard a kind of whoosh. I looked up and saw the whole carriage engulfed in flames making its way towards me," Ola Fayankinnu, who was on the train, told Reuters."A lot of people were trampled on. There were phones, hats, bags all over the place and when I looked back I saw a bag with flames. People were crying, shocked, a few people had been injured, some people had been trampled."Outside the station, a woman was sitting on a pavement with a bandage around her leg, while armed police patrolled. A Reuters witness saw a woman being carried off on a stretcher with her legs covered in a foil blanket."We are aware of an incident at #ParsonsGreen tube station. Officers are in attendance," London police said on Twitter. "We would advise people to avoid the area."Police said they were aware of reports on social media but said they would release facts regarding the incident once they could be sure of their accuracy.'Keep calmtarget="_blank"'>Britain has suffered four attacks blamed on terrorists so far this year which killed 36 people. In 2005, 52 people were killed when four British Islamists carried out suicide bomb attacks on three London underground trains and a bus.