GREENFIELD, IOWA -- A deadly tornado that wreaked havoc in the small city of Greenfield, Iowa, left four people dead and nearly three dozen injured, officials said, while a fifth person was killed elsewhere.

The twister that tore through the city on Tuesday was rated at least an EF-3 by the National Weather Service and was so destructive that it took authorities more than a day to account for the area's residents.

It’s believed that the number of people injured is likely higher, the Iowa Department of Public Safety said.

The fifth person was killed about 25 miles (40 kilometres) from Greenfield when her car was blown off the road in a tornado, according to the Adams County Sheriff’s Office. Monica Zamarron, 46, died in the crash Tuesday afternoon, officials said.

Officials haven't yet released the names of the other victims.

The severe weather turned south Wednesday. In Texas, officials issued an emergency declaration in Temple, a city of more than 90,000 people north of Austin, after powerful storms ripped through the area. Thousands of residents lost power, schools cancelled Thursday's classes and nearby Fort Cavazos reported significant debris blocking traffic at the Army installation.

In Iowa, the Greenfield tornado obliterated homes, splintered trees and crumpled cars in the town of 2,000 about 55 miles (89 kilometres) southwest of Des Moines. The twister also crumpled massive power-producing wind turbines outside the city.

Greenfield resident Kimberly Ergish and her husband dug through the debris field Wednesday that used to be their home, looking for family photos and other salvageable items. There wasn’t much left, she acknowledged. The reality of having her house destroyed in seconds hadn’t really set in.

“If it weren’t for all the bumps and bruises and the achy bones, I would think that it didn’t happen,” Ergish said.

This is a historically busy tornado season in the U.S., in an era when climate change is heightening the severity of storms around the world. April had the country's second-highest number of tornadoes on record.

Through Tuesday, 859 tornadoes had been confirmed this year, 27 per cent more than the U.S. sees on average, according to NOAA’s Storm Prediction Center in Norman, Oklahoma. Iowa has so far recorded the most, with 81 confirmed twisters.

On Tuesday alone, the National Weather Service said it received 23 tornado reports, with 21 in Iowa.

Tuesday's storms also pummeled parts of Illinois and Wisconsin, knocking out power to tens of thousands of customers.

Evidence of 'intense' tornado

The Greenfield tornado was at least an EF-3, according to initial surveys, and more damage assessments could lead to a more powerful ranking, the National Weather Service said.

The tornado appeared to have been on the ground for more than 40 miles (64 kilometres), AccuWeather Chief Meteorologist Jon Porter said. A satellite photo taken by a BlackSky Technology shows where the twister gouged a nearly straight path of destruction through the town, just south of Greenfield’s center square.

“Debris was lifted thousands of feet in the air and ended up falling to the ground several counties away from Greenfield. That’s evidence of just how intense and deadly this tornado was," Porter said.

People as far as 100 miles (160 kilometres) away from Greenfield posted photos on Facebook of ripped family photos, yearbook pages and other items that were lifted into the sky by the tornado.

About 90 miles (145 kilometres) away, in Ames, Iowa, Nicole Banner found a yellowed page declaring “This Book is the Property of the Greenfield Community School District” stuck to her garage door like a Post-It note after the storm passed.

“We just couldn’t believe it had travelled that far,” she said.

White House Press Secretary Karine Jean-Pierre said FEMA’s administrator would be in Iowa Thursday and that the White House was in touch with state and local officials. She said they were “praying for those who tragically lost their lives” and wished those injured a “speedy recovery.”

Greenfield's 25-bed hospital was among the buildings damaged, so at least a dozen injured people had to be taken elsewhere. Hospital officials said in a Facebook post Wednesday that they'll remain closed and full repairs could take months. Meanwhile, an urgent care clinic was set up at the elementary school, with primary care services to start there Thursday, the post said.

Residential streets that on Monday were lined with old-growth trees and neatly-appointed ranch-style homes were a chaotic jumble of splintered and smashed remnants by Wednesday. Many basements where people took shelter were exposed, and front yards were littered with furniture and toys and Christmas decorations.

Roseann Freeland waited until the last minute to rush with her husband to a concrete room in their basement. Seconds after the twister passed, her husband opened the door "and you could just see daylight,” Freeland said. “I just lost it. I just totally lost it.”

Beck reported from Omaha, Nebraska. Associated Press writers Steve Karnowski and Trisha Ahmed in Minneapolis; Heather Hollingsworth in Mission, Kansas; and Jim Salter in O'Fallon, Missouri, contributed.