An explosion at a fertilizer plant leveled dozens of homes in a small Texas town late on Wednesday, killing as many as 15 people, injuring more than 160 others and spewing toxic fumes that forced the evacuation of half the community, authorities said.

Police initially estimated that between five and 15 people perished in the blast, which rocked the town of West, located about 32 km north of Waco and 130 km south of Dallas, shortly before 8 pm on Wednesday.

A man injured in a fertilizer plant explosion in West, Texas, is treated on Wednesday. Up to 15 people were estimated killed in the blast that shook the ground with the strength of a small earthquake and could be heard dozens of kilometers away. Jerry Larson / AP-Waco Tribune-Herald

Public safety officials said they expected the death toll to climb as search teams combed through the rubble of the demolished West Fertilizer Co plant and surrounding homes.

"I've never seen anything like this," McLennan County Sheriff Parnell McNamara said. "It looks like a war zone with all the debris."

Ground motion from the blast, triggered by a fire of unknown origin at the plant, registered as a magnitude-2.1 seismic tremor that was felt in Dallas and beyond, the US Geological Survey reported.

Waco Police Sergeant W. Patrick Swanton said investigators would examine whether the blaze was the result of foul play or a chemical reaction, adding that the blast site was being treated as a crime scene for the time being.

"We are not indicating that it is a crime, but we don't know," Swanton told reporters early on Thursday, some nine hours after the blast. "What that means to us is that until we know it is an industrial accident, we will work it as a crime scene." He said there was no immediate evidence of a crime.