A massive explosion at a fertilizer plant in a small Texas town has left a number of people dead, caused a “tremendous amount of injuries” and damaged dozens of nearby buildings.

The number of people injured could soar above 100, according to Texas Department of Public Safety spokesperson D. L. Wilson. He could not confirm the number of fatalities, but said he hoped to have more concrete information by early Thursday morning.

Wilson said “at least 50 to 75” buildings in West, north of Waco, had been devastated, and a nursing home with 133 people inside had to be evacuated.

A house-by-house search for survivors was expected to continue throughout the night. Wilson said he had walked through the blast zone and some of the buildings looked like “standing skeletons.”

The huge blast tore apart the West Fertilizer facility in the community of about 2,800 people.

The mayor of West said late Wednesday that he didn’t know how many people were killed.

"We've got a lot of people who are hurt, and there's a lot of people, I'm sure, who aren't gonna be here tomorrow," Muska said. "We're gonna search for everybody. We're gonna make sure everybody's accounted for. That's the most important thing right now."

Tommy Muska said buildings in a five-block radius from the plant were severely damaged, including the West Raven Nursing Home.

Witnesses reported hearing a loud blast and seeing huge flames at the fertilizer plant shortly before 8 p.m.

Aerial footage shows the plant and surrounding area still burning in the dark hours after the explosion. A triage centre had been set up at a nearby football field to treat some of the injured.

Dozens of people are gathering at what appears to be a community centre. Local roads are jammed with emergency vehicles.

Debby Marak told The Associated Press that she drove to the plant after seeing smoke in the area. When she arrived, two boys ran towards her, screaming that authorities had warned everyone to leave the area immediately.

Marak managed to drive about a block away before the plant exploded.

"It was like being in a tornado. Stuff was flying everywhere. It blew out my windshield," the 58-year-old told AP by phone.

"It was like the whole earth shook."

The regional public school district announced that all campuses will be closed Thursday and Friday.

“Stay away from all school property,” it warned on Twitter.

Texas Governor Rick Perry issued a statement late Wednesday saying: “We are monitoring developments and gathering information as details continue to emerge about this incident. We have also mobilized state resources to help local authorities.

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

A hotline has been set up for those looking for information about their loved ones: 254-202-1100.

The huge explosion follows the Boston Marathon bombings on Monday and also comes on the anniversaries of two other American tragedies: The 50-day Waco siege, which ended on April 19, 1993, and the Oklahoma City bombing, which happened on April 19, 1995.

The Waco siege, which happened just southeast of where the West fertilizer plant exploded, left 76 people dead.