Police in Texas have been unable to establish how many people remain trapped after an fertilizer plant explosion that killed up to 15 people. Police are keeping an open mind about the cause of the blast.
Rescue teams on Thursday searched the rubble and wreckage of the plant as well as dozens of demolished homes nearby.
Police said the official estimate of fatalities remained vague, at between five and 15, as the search continued in the town of West, some 32 kilometers (20 miles) north of the city of Waco.
Waco Police Sergeant William Patrick Swanton said officials were going from building to building in the devastated neighborhood around the plant. A group of firefighters and one law enforcement officer who responded to a fire call at the plant were among those who remained unaccounted for.
"At some point this will turn into a recovery operation, but at this point, we are still in search and rescue," said Swanton.
Likened to nuclear bomb, tornado
The explosion in West, some 130 kilometers south of Dallas, was heard over a wide area, and sent flames and embers high into the night sky. The effect was variously described as having been like a tornado or nuclear bomb. As well as the fatalities, some 160 people were said to have been injured.
The blast occurred at about 7:50 p.m. local time, some 50 minutes after first responders were said to have arrived at the scene of the reported initial fire.
"We are not indicating that it is a crime, but we don't know," Swanton. "What that means to us is that until we know it is an industrial accident, we will work it as a crime scene."
Officials said that up to 75 houses had been damaged, with a nearby apartment building effectively reduced to a "skeleton."
Obama laments loss
President Barack Obama said the federal government was monitoring the response at a state and local level, and offered his condolences in a statement.
"West is a town that many Texans hold near and dear to their hearts, and as residents continue to respond to this tragedy, they will have the support of the American people," Obama said.
Texas Governor Rick Perry said personnel from several state agencies had been sent to help with the response.
With a population of about 2,800 people, West has a large Czech community that dates back to the late 1800s. The Czech Foreign Ministry in Prague said that its Washington ambassador, Petr Gandalovic, was travelling to the town to assess what his government could do to help.
rc/jr (AP, AFP, dpa, Reuters)