Scores of people are injured and an unknown number are dead after a huge explosion at a fertiliser plant near Waco in the US state of Texas.
Dozens of homes and buildings have been destroyed, and several are still on fire, after the West Fertilizer plant exploded at about 19:50 (00:50 GMT).
Some people are thought still to be trapped in buildings and a number of firefighters are reported missing.
Emergency services officials said ammonia may have caused the explosion.
It has been reported the company had 54,000lbs (20 tonnes) of anhydrous ammonia on sit
It was like being in a tornado. Stuff was flying everywhere. It blew out my windshield. It was like the whole earth shook.”
Debby Marak, witness
Firefighters had been tackling a blaze at the plant when the explosion in West, a town of about 2,700 people some 20 miles (32km) north of Waco, occurred.
Police said the half the town had been evacuated, amid fears of possible further explosions or a leak of toxic gas.
The plant is right on the edge of town, only a few hundred metres from houses, a school and nursing home.
Sgt William Swanton of the Waco police department said power to the town had been shut off to prevent further accidents.
He confirmed there were deaths, but could not give a figure.
Police have been conducting house-to-house searches to check for casualties.
‘Like a war zone’
TV images showed streams of emergency vehicles descending on the site and ambulance crews using a nearby sports field as an emergency treatment area. The injured were being carried to hospital not just in ambulances but in police squad cars and helicopters.
Glenn A Robinson, chief executive of Hillcrest Baptist Medical Center in Waco, told CNN that his hospital had received 66 injured people including 38 who were seriously hurt.
He said the hospital was seeing “everything from orthopaedic injuries to patients that are experiencing serious blood loss”.
McLennan County Sheriff Parnell McNamara said: “It’s a lot of devastation. I’ve never seen anything like this. It looks like a war zone with all the debris.”
A nursing home was caught in the explosion and some people were believed trapped inside.
Witness Debby Marak told the Associated Press news agency that she had seen smoke coming from the area near the plant and had driven over to see what was happening.
She said that when she arrived, two boys ran towards her screaming that the authorities had told them to leave because the fertiliser plant was going to explode.
She said she drove a short distance before the blast happened.
Another resident told KWTX-TV that she heard several explosions from 13 miles (20km) away.
“It sounded like three bombs going off very close to us,” said Lydia Zimmerman.
Texas Governor Rick Perry said in a statement: “We are monitoring developments and gathering information as details continue to emerge about this incident.
“We have also mobilised state resources to help local authorities. Our thoughts and prayers are with the people of West, and the first responders on the scene.”
The Dallas Morning News reported that West Fertilizer had told the Environmental Protection Agency that it presented no risk of fire or explosion.