• IN PICTURES: WEST PLANT FERTILIZER EXPLOSION
• Unknown girl cries: "Dad, dad, I can't hear anything."
• Explosion at fertiliser plant north of Waco, Texas  
• West Plant Fertilizer explosion 'like a bomb'

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

Already, an unknown girl has become the face of the West Fertilizer 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.

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

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.

With smoke rising in the distance, a law enformcement officer runs a check point at the perimeter about half a mile from the West Fertilizer Company April 18, 2013 in West, Texas. AFP Photo

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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.

Firefighters conduct search and rescue of an apartment building destroyed by the explosion at the West Fertilizer Co., in Texas. Picture: AP Photo/LM Otero