Texas blast: seven questions raised by the West disaster
As many as 15 people feared dead after a massive explosion at a fertiliser plant near Waco, Texas
RESCUE workers are desperately combing rubble and ruined houses for survivors after the massive explosion at a fertiliser plant in the Texas town of West that is believed to have killed up to 15 people and injured more than 160.
Patrick Swanton, a police officer from nearby Waco, said rescuers are going from building to building in the decimated area surrounding the plant. "They have not gotten to the point of no return where they don't think that there's anybody still alive," he told the Denver Post, but said he did not know how many people had been rescued.
One witness compared the scale of devastation to the 1995 bombing of the Alfred P. Murrah building in Oklahoma City. The blast, which levelled houses and public buildings in West - about 31km from Waco - was heard 65 miles away in Dallas and triggered an enormous plume of smoke. Here are seven key questions raised by the horrific incident:
Where did the blast occur? The town of West is located in the north-central part of Texas and has a population of about 2,700. It has a strong Czech heritage due to immigrants from Eastern Europe who arrived there in the 1880s. The blast happened at the West Fertilizer Plant.
How many people have been injured? A spokesman for the local Department of Public Safety said: "We do have fatalities. The number is not current. It could go up by the minute.". Reports suggest the death toll is somewhere between 5 and 15. There are grave fears for six volunteer fire fighters who arrived at the site to attend a fire about 30 minutes before the blast occurred at 8.00pm on Wednesday evening local time. More than 100 people are known to have been injured and police are conducting searches of up to 75 houses damaged by the explosion in an effort to locate more victims.
What is the scale of the damage? The blast measured 2.1 on the Richter scale and there are reports that buildings "within a two-block radius have been levelled". Buildings within a five-block radius have been extensively damaged. A tower block containing 50 apartments was "stripped" by the explosion and now resembles a "skeleton", CNN reports. The West Rest Haven nursing home near the plant collapsed and more than 130 residents were evacuated, and a school is reported to be on fire.
What caused the blast? Emergency services officials told the BBC that ammonia may have caused the explosion and it has been reported the fertiliser company had about 20 tonnes of anhydrous ammonia on site. Described as "a low-cost, highly effective nitrogen-based fertilizer", anhydrous ammonia is essentially ammonia in its liquid or gas state. It has to be stored at high pressure and is corrosive to copper, silver, aluminium, zinc and alloys. It reacts with body moisture, so it may burn body tissue - skin, eyes, mouth, throat, lungs and stomach - on contact, or if inhaled or swallowed, the Daily Mail reports.
Might there be another explosion? Officials had concerns about a second fertiliser tank at the West plant. A spokesman for Texas senator Brian Birdwell said he believed evacuations are in place to make sure everyone gets away from the area safely in case of another explosion.
Was the plant thought to be dangerous? The plant informed the Environmental Protection Agency that it presented no risk of fire or explosion, the Dallas Morning News reports. Prior to the blast it apparently filed a report with the EPA that said "even the worst-case scenario wouldn't be that dire: there would be a 10-minute release of ammonia gas that wouldn't kill or injure anyone".
Was it an accident or something more sinister? At this stage, it appears overwhelmingly likely that the blast was not the result of criminal activity or an act of terrorism. That hasn't stopped some commentators attaching some significance to the fact it occurred a few days after the Boston Marathon bombings. It has also been noted that 19 April is the 20th anniversary of the Waco Siege where 76 people were killed when the FBI stormed a compound belonging to the Branch Davidian religious sect. The Oklahoma bombing took place on the same date – 19 April - in 1995.