Texas Fertiliser Blast: Arson Not Ruled Out

Investigations into a deadly blast at a Texas fertiliser plant have failed to identify a cause.

State Fire Marshal Chris Connealy said officials were still classifying the cause of the fire that sparked the deadly explosion as undetermined - but have not ruled out criminal activity.

The April 17 blast killed 15 people, injured 200 and levelled part of the town of West, which has a population of around 2,800.

The explosion was so powerful that it registered on the Richter scale as a 2.1 earthquake, and debris from it was found up to 2.5 miles away.

The plant exploded as firefighters battled a blaze that had somehow broken out on the plant's grounds near stores of highly explosive ammonium nitrate - a chemical used as a fertiliser that also can be used as an alternative to dynamite.

Officials said three possible causes of the fire were a malfunction in the plant's 120-volt electrical system, a golf cart that may have given off a spark, or it may have been started intentionally.

Investigators said between 28 and 34 tonnes of ammonium nitrate exploded in two blasts just milliseconds apart.

Another 20 to 30 tonnes also stored on the site did not explode. A nearby railcar holding an additional 100,000 tonnes of ammonium nitrate was damaged.

Texas Governor Rick Perry praised the tiny town and his state for coming together in the wake of the disaster.

Mr Perry said: "This tragedy has shown the world the definition of compassion, from volunteer firefighters across the state rushing to help their colleagues at the scene, to friends, neighbours and Texans stepping in to help those who lost so much in the blast."