LONDON, Sept. 15 (Xinhua) -- London subway blast was caused by detonation of improvised explosive device, British police said Friday.

A white plastic container caused fire on a packed rush-hour carriage at Parsons Green subway station in west London at around 8:20 a.m. local time on Friday.

Police said that 18 people were rushed to hospitals following the blast and there were no serious and life-threatening injuries.

The device is understood to have a timer, local media reports said.

London explosive ordinance disposal team is looking for forensic clues on the scene as nurseries in the neighbourhood were evacuated.

The incident created chaos in the area as the subway service was shut down and police stopped people from getting close.

The blast took place after three deadly attacks in London this year -- Westminster Bridge, London Bridge and Finsbury Park, and one in Manchester at an Ariana Grande concert.