WARNING: Some may find this distressing. Terrifying phone footage of the explosion near Waco, Texas is filmed by a father, leaving his daughter unable to hear.

THE death toll has been revised as a search is under way to find people trapped after an explosion from a fertiliser plant.

Already, 12-year-old Khloey Hurtt has become the 'face' of the West Fertiliser Plant disaster, after a video of her crying out "Dad, dad, I can't hear anything, please get me out of here," went viral across the world. The footage was shot by Derrick Hurtt and the voice belongs to his 12-year-old daughter Khloey.

Police in Texas say between five and 15 people were killed in the blast that also injured as many as 200 others.

Sergeant Patrick Swanton, of Waco Police, said while the search "from house to house" for people trapped in buildings was continuing, the actual number of fatalities was unknown.

Sergeant Swanton said police were still pulling people out of the plant's surrounding buildings and he could not estimate how many people might still be trapped.

Earlier, a senior doctor said he had been told told by firefighters that up to 70 people had been killed and hundreds injured in the blast, which destroyed numerous buildings including a nursing home and large apartment block.

Prompted on this by reporters, who noted that officials were using an "abundance" of caution in giving figures, Sergeant Swanton said: "I cannot confirm that at all, I don't know who that doctor was, I have not heard that number."

However, he said that firefighters and a police officer remained "unaccounted for" after the explosion.

Sergeant Swanton said it was not clear if the blast was a criminal act.

"I heard that there was a helicopter on the scene that sustained some damage ... we are trying to confirm that, " he said.

Earlier, Trooper D.L Wilson confirmed there had been deaths but did not give an exact number, saying the toll could go up "by the minute".

The blast at the fertiliser plant, which came after a fire, devastated the town of West, north of Waco, destroying numerous buildings including a nursing home and a large apartment block of 50 units. Residents have been evacuated due to toxic fumes.

Firefighters have contained the blazes and emergency workers worked throughout the night to search for people who may be trapped in the town's collapsed buildings.

In the hours after the blast, residents wandered the dark, windy streets searching for shelter. Among them was Julie Zahirniako, who said she and her son, Anthony, had been playing at a school playground near the fertiliser plant when the explosion hit. She was walking the track, he was kicking a football.

The explosion threw her son a metre in the air, breaking his ribs. She said she saw people running from the nursing home and the roof of the school lifted into the sky. "Hit the ground, hit the ground," Ms Zahirniako heard a neighbour yell.

"The fire was so high," she said. "It was just as loud as it could be. The ground and everything was shaking."

William Burch and his wife, a retired Air Force nurse, entered the damaged nursing home before first responders arrived. They split up, searching separate wings, and found residents in wheelchairs trapped in their rooms. The halls were dark and the ceilings had collapsed. Water filled the hallways and electrical wires hung eerily from the ceilings.

"They had Sheetrock that was on top of them. You had to remove that," Mr Burch said. It was "completely chaotic."

LIVE UPDATES BELOW. ALL TIMES IN AEST.

4.30am Rain and heavy winds have helped dissipate chemicals that may have been released by the fertiliser plant explosion and fire, reports CNN. The Texas National Guard has sent 21 troops from a civil support team to monitor air quality near the blast.

3.40am There are concerns for people trapped by rubble who are enduring unseasonally cold overnight temperatures, falling below 10 degrees Celcius; around 10 degrees cooler than would be normal at this time of year.

3.05am Texas Governor Rick Perry has told a press conference he is seeking a federal disaster declaration which would make additional funds available. "This tragedy has most likely hit every family, it has touched practically everyone in that town," Governor Perry said.

2.19am Authorities said the fertiliser plant made materials similar to the ammonium nitrate used in the 1995 Oklahoma City bombing. It also was used in the first bombing attempt at the World Trade Center in 1993. Ammonium nitrate is stable, but if its components are heated up sufficiently, they break apart in a runaway explosive chemical reaction, said Neil Donahue, professor of chemistry at Carnegie Mellon University. Concern at the West fertiliser plant is centred on the use of anhydrous ammonia.

1.52am Search and rescue efforts in West could be complicated by a storm system heading into the area, with forecasters predicting heavy rains, and winds possibly heavy enough to spawn tornadoes.

1.47am KCENTV.com is reporting as many as 200 injured as a result of the fire and explosion.

1.34am US President Barack Obama offered aid through the Federal Emergency Management Administration, and promised "to make sure there are no unmet needs as search and rescue and response operations continue."

1.26am In Prague, the foreign ministry said its ambassador to Washington, Petr Gandalovic, was travelling to West to study the possibility of providing aid from his government for the injured and relatives of the victims. West is home to a thriving Czech community dating back to the late 1800s.

1.13am Police Sergeant Patrick Swanton says that police are concerned about "a small amount of looting" that has broken out at unattended homes and businesses.

12.13am The US Chemical Safety Board is deploying a large investigation team to West. An Alcohol, Tobacco and Firearms national response team that investigates all large fires and explosions is also coming in, bringing fire investigators, certified explosives specialists, chemists, canines and forensic specialists.

12.06am: Resident Julie Zahirniako tells AP the explosion threw her son, Anthony a metre in the air, breaking his ribs.

11.51pm: Sergeant Patrick Swanton of Waco Police says the firefighters who are missing were actively fighting fire at time of the explosion, reports Kirsten Crow of Wacotrib.com.

9.56pm: 3-5 firefighters still missing, including Morris Bridges. His photo has been posted on Twitter after his sister raised the alarm. His car is still at the firehouse. He is a father of three, Reporter Ray Villeda of NBCFW tweeted this photo.

9.51pm: Roughly 85 students - some from Baylor University, some from high school and McLennan Community College, among others - gathered for a midnight prayer vigil at Baylor’s Waco Hall, wacotrib.com reports.

9.20pm: West Mayor Tommy Muska has held a press conference and said we "ask for your prayers." He said between 50-60 homes damaged, according to WacoTrib.com reporter Kirsten Crow who attended the press conference.

8.07pm: Police in Texas say between five and 15 people were killed in the blast that also injured more than 160 others, AP reports.

7.21pm: Pope Francis has tweeted: "Please join me in praying for the victims of the explosion in Texas and their families."

6pm: West's Mayor Tommy Muska tells CNN there is "no indication this is anything but an accident".

5.40pm: The US Geological Survey says the explosion in West registered as a 2.1-magnitude event - even though nearest sensor is 40kms away.

5.30pm: A West city council member says a four-block area near the plant has been "totally decimated".

5pm: More areas in West could be evacuated if the wind changes, Sky News is reporting.

4.51pm: Country star Willie Nelson, who was born in the nearby town of Abbott, says he is praying for those affected by the devastating blast.

"West has been in my backyard all my life," he tweeted. "My heart is praying for the community that we call home."

4.40pm: The fertiliser plant that exploded in West Texas reported to the Environmental Protection Agency and local public safety officials that it presented no risk of fire or explosion, documents show.

West Fertilizer Co. reported having as much as 24,494kg of anhydrous ammonia on hand in an emergency planning report required of facilities that use toxic or hazardous chemicals.

But the report, reviewed on Wednesday night by The Dallas Morning News, stated "no'' under fire or explosive risks. The worst possible scenario, the report said, would be a 10-minute release of ammonia gas that would kill or injure no one.

The second worst possibility projected was a leak from a broken hose used to transfer the product, again causing no injuries.

4.20pm: CNN reports that 156 victims have been admitted to three area hospitals following the fertiliser plant explosion in West, Texas.

3.15pm: Trooper D.L. Wilson of the Department of Public Safety said there was a "tremendous amount of injuries and we do have confirmed fatalities".

"(It was ) just like Iraq. Just like the Murrah building in Oklahoma City," he said.

The fire is still smouldering and toxic fumes have caused an area of up to 10 blocks to be evacuated around the plant.

"We cannot get firefighters in there," he said.

So far, all the known injured have been taken care of, he said.

"We're going to go back in and do another house by house search ... that is going to be going on all night.

"(An ) apartment complex with 50 units is like a skeleton standing up.''

3.05pm: Trooper D.L. Wilson says 50 to 75 houses have been destroyed in the West blast.

"We're worried about people right now, not property," he said.

The trooper told a media conference that 50 units in an apartment block had been destroyed but firefighters were unable to get to the scene due to fumes.

He did not give a death toll from the blast. "The number is not confirmed yet, it could go up by the minute," he said.

2.58pm: Fire officials fear that the number of casualties could rise as high as 60 to 70 dead, said Dr George Smith, the emergency management system director of the city.

"That's a really rough number, I'm getting that figure from firefighters, we don't know yet," he said.

"We have two EMS personnel that are dead for sure, and there may be three firefighters that are dead."

2.56pm: The mayor of West believes about 60 buildings have been levelled in the blast.

2.55pm: Hillcrest Medical Centre's CEO on the injured: "Many of these looked just like regular families: a mom, dad, children coming in together."

2.46pm: Police in Waco say the scene of the explosion is still "very hectic". Officers are trying to secure the surrounding neighbourhoods and evacuate the injured.

2.30pm: "Every house within about four blocks is blown apart," a witness has told the Waco Tribune.

2.20pm: West EMS Director Dr George Smith says as many as 60 or 70 people have died and at least 100 were injured in the fertilizer plant blast. A rescuer earlier said he knew of five deaths.

West Mayor Tommy Muska said at a news conference however, that he doesn't yet know how many people were hurt or killed in the blast explosion.

2.07PM: The Federal Aviation Administration has put a no-fly zone into effect 5km around West and below 3,000 feet.

The FAA said only emergency aircraft were permitted to fly in the area.

2PM: Pictures of the blast have been posted on social media with people sending their messages of support to the people of West.

1.52PM: Waco police said on Twitter the blast scene was devastating. "Surreal scene in West. Helicopters hanging over the city fire police ambulances everywhere."

1.43PM: Five firefighters and one police officer believed to be among the dead.



1.42PM: AT least 200 people are believed to have been injured in the blast, 40 critically, ABC news reports. Between 75-100 houses and businesses have reportedly been destroyed.



1.40PM: Hillcrest Baptist Medical Center CEO Glenn Robinson said the hospital had treated 61 patients so far, but there had been no fatalities at the hospital.

1.30PM: West EMS Director Dr George Smith told KWTX up to 70 people died and hundreds were injured in the explosion.

1.26PM: Texas Governor Rick Perry released a statement following the explosion.

“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," he said.

"Our thoughts and prayers are with the people of West, and the first responders on the scene.”

EARLIER

An emergency triage area was set up at a nearby football field with at least nine medical helicopters landing to evacuate the injured, while police officers drove others to the West to Hillcrest Hospital in their patrol cars.

The triage area had to be moved following orders for the town to evacuate.

Hospitals have been warned to expect up to 100 people with injuries from the blast with the Hillcrest Baptist Medical Center issuing a call for all staff to attend.

Firefighters have been forced to retreat from the blaze at the plant after a second propane tank used to transport anhydrous ammonia caught fire. Crews are refilling their tanks from the local swimming pool as they battle several blazes ignited by the blast.

"We've got a lot of buildings on fire, we still have people trapped in an apartment building and possibly in a rest home," and emergency services operator said.

"We got reports of two kids on the second floor, about 50 foot from the north end," another emergency worker said. It is believed they were talking about the apartment building.

Several homes within two-blocks of the plant are also on fire.

"The fertiliser plant down here exploded" Jason Shelton, a clerk at the Czech Best Western Hotel, told the Dallas news.

“It was a small fire and then water got sprayed on the ammonia nitrate and it exploded just like the Oklahoma City bomb.

“There’s houses leveled that were right next to it. We've got people injured and possibly dead

“I live about a thousand feet from it and it blew my screen door off and my back windows.

The Waco Tribune reports several firefighters are among those critically injured in the blast, which occurred when they were trying to douse an earlier fire that had rekindled.

A radio dispatcher called for several ambulances to attend saying "we do have a lot of injured here".

Another dispatcher said people were still trapped in the fire saying "I need anybody and everybody you can send".

Crystal Anthony told the Waco Tribune she and her daughter were “knocked back” by the blast while standing several blocks from the fertiliser plant.

KWTX news reports West Middle School was one of the buildings on fire.

Lydia Zimmerman told KWTX: “It sounded like three bombs going off very close to us" while others said the explosion shook their homes.



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A woman travelling along the freeway near where the explosion happened told KWTX that she and her boyfriend saw a massive fireball shoot into the air.

Authorities are going door to door in the area checking on residents. The explosion knocked out power to a large area surrounding the plant.

The explosion was felt up to 100km away in Dallas, with many residents believing it was an earthquake.



It comes after a week where America has been on high alert after the Boston Marathon bombings which killed three people and wounded another 170.

Although there is no suggestion that the events are related, 'Fahrenheit 9/11' filmmaker and author Michael Moore has tweeted: “This is the anniversary week of the Columbine massacre, the Oklahoma City bombing, the Virginia Tech massacre, the Bay of Pigs, and Waco.

The Waco siege ended on April 19, 1993, the Bay of Pigs on April 17, Columbine on April 20, Oklahoma on April 19 and Virginia Tech on April 16.



