Lincoln, NE – Amid the rising smoke and exploding ammunition, Kiera Mendez saw the definition of community as she sprinted to help.

Moments before an apparent natural gas explosion leveled a southeast Lincoln home on Monday afternoon, the 21-year-old nursing student had been sitting on her couch.

The blast that shook her house — and that residents felt all across the city — sent her scrambling to the scene three blocks away.

“You get there, and the community is rallying there for these two people that probably half of us don’t even know,” Mendez said.

Two people, believed to be residents of the leveled home at 5601 S. 78th St., were taken from the scene with life-threatening injuries.

Batallion Chief Jeremy Gegg said fire investigators haven’t confirmed the cause, but think it may have been a natural gas explosion.

The blast just after 4:30 p.m., shortly after dozens of students walked home from the first day of classes at nearby Maxey Elementary, scattered debris for blocks north of 77th Street and Old Cheney Road. As many as eight homes nearby were also damaged.

As she reached the scene, Mendez saw neighbors scrambling to surrounding homes, checking for any injured.

She ran through debris, ignoring warnings of exploding ammunition from the leveled home.

“All you could smell was the house burning,” the Kaplan University nursing student said.

Along with other medical professionals she didn’t know, Mendez tended to an elderly man who had been burned, she said.

They helped carry him from the backyard while others cared for the man’s wife, she said, performing basic first aid until paramedics arrived.

Hours later, about 50 people stood near 77th Street and Eastview Drive, some waiting to return to their homes. Gas and power was shut off in the area as crews conducted a home-to-home inspection. The blast moved some from their foundation.

Bryce Rowell, who lives in the 5600 block of South 77th Street, wasn’t home when the explosion happened.

“When the neighbors called, they said to expect to walk into a war zone.”

Michelle Camp, who lives just north of the scene near 78th Street and Karl Drive, likened it to a sonic boom.

“The whole house just shook,” she said.

Diana McCoy, who lives nearby on 77th Street, said she saw flames and heard several explosions after she left her home.

“We were downstairs and we thought a plane hit our house. The concussion of it was just incredible.”

The windows in McCoy’s home were shattered, the back door came unhinged and the drywall in her garage is significantly damaged. Her TV, photos and anything in her cupboards fell down.

“I’m glad it wasn’t our house, and I’m praying for the people who own that home,” she said.

Black smoke rising from the area was visible from downtown Lincoln as crews reached the scene after 4:30 p.m.

Tom Casady, the city’s public safety director, told KLIN-AM radio that he couldn’t recall a natural gas explosion of this proportion in Lincoln — where a structure was leveled — in his tenure.

There were no known reports of a gas line rupture in the area, but residents confirmed crews have been doing underground work nearby and “dig tickets” have been filed with Nebraska 811 during recent weeks. Technicians with Black Hills Energy responded to the scene following the blast and a spokeswoman said an investigation into what caused the explosion was underway.

Members of the State Fire Marshal’s office, along with local fire investigators, joined Lincoln Police and Lincoln Fire and Rescue at the location.

At 9 p.m., nearby homeowners worked to board up busted out windows, hoping to be able to spend the night at home. Bricks and shattered boards lay scattered across the area. Insulation and wood littered roofs.

Kylan Young, 12, was walking with a friend in the neighborhood when they heard the explosion and saw the aftermath. He went into his cousin’s friend’s home, which is across the street from the blast, to help find their dog.

“Everything in the house looked like a tornado went through it,” Young said.

Earlier, Susan Napolitano, who lives south of the destroyed home, was waiting with other neighbors and onlookers where the scene was cordoned off at 78th and Casey Lane.

Napolitano, who was at work at the time of the explosion, said she had text messages from friends asking if her house had blown up.

“I’m surprised anyone made it out alive,” she said.

Mendez, as she returned to the home she moved into in June, found her cellphone — illuminated by flashing emergency lights — on the street as she walked away from the scene.

It’s unlike anything she’s ever seen, she said.

Monday night her thoughts were with the neighborhood couple taken to the hospital.

She’s hopeful they can recover, she said.

“That’s all you can hope for.”