West Mayor Tommy Muska told reporters that his city of about 2,800 people needs "your prayers."
"We've got a lot of people who are hurt, and there's a lot of people, I'm sure, who aren't going to be here tomorrow," Muska said. "We're going to search for everybody. We're going make sure everybody's accounted for."
At the Hillcrest Baptist Medical Hospital in Waco, elderly people were wheeled in on stretchers. A man in a wheelchair with his T-shirt covered in blood winced as teams tended to his wounds.
About a half-hour before the blast, the town's volunteer firefighters had responded to a call at the plant, Swanton said. They immediately realized the potential for disaster because of the plant's chemical stockpile and began evacuating the surrounding area.
The blast happened 20 minutes later.
The main fire was under control late Wednesday, but residents were urged to remain indoors because of the threat of new explosions or leaks of ammonia from the plant.
Firefighters used flashlights to search the still-burning skeleton of an apartment complex that was all but destroyed. A flood-lit football field initially was used as a staging area, then other triage centers sprung up around the blast site.
First-responders evacuated 133 patients from the nursing home, some in wheelchairs. Many were dazed and panicked and did not know what happened.
Erick Perez was playing basketball at a nearby school when the fire started. He and his friends thought nothing of it at first, but about a half-hour later, the smoke changed color. The blast threw him, his nephew and others to the ground and showered the area with hot embers, shrapnel and debris.
"The explosion was like nothing I've ever seen before," Perez said. "This town is hurt really bad."