The initial blast occurred at the West Fertilizer Plant in West, Texas state just before 8 p.m. Wednesday. The explosion sent at least 180 people to hospitals and flattened buildings.
Witnesses reported heavy fire or concussive damage to a middle school, homes and an apartment complex near the plant, as well as to a nursing home, where more than 130 residents were evacuated, according to Muska.
The blast was registered as a 2.1 magnitude seismic event, according to the US Geological Survey.
Buildings in a radius of about five blocks around the plant -- including at least 60 more homes -- were heavily damaged by the blast, officials said.
It was felt 20 to 30 miles away, witnesses said, and near the plant burned buildings, knocked down people, blew out windows and, according to Wilson, left the damaged apartment complex looking like "just a skeleton standing up."
There were subsequent explosions around 10 p.m., ABC News affiliate WFAA reported. The cause of the explosions was unconfirmed, but a dispatcher was heard warning crews to move away from chemicals in unexploded tanks.
Most fires were contained early Thursday, officials said, but they continued to burn.