Nebraska State Patrol announced at a press conference that Jason Jones, 42, had been taken into custody after a SWAT team burst into his home in Elm St, Laurel, just after 2.30am on Friday.
Police named the four victims as Michelle Ebling, 53, who lived on the 200 block of Elm St, Gene Twiford, 85, his wife, Janet Twiford, 86, and their 55-year-old daughter Dana, who perished on the 500 block of Elm St.
Ms Ebling lived directly opposite the suspect, police said.
“I want to acknowledge the indescribable that this community is experiencing right now,” state police colonel John Bolduc said at a news conference at the Laurel Fire Station on Friday morning. “And that’s going to be compounded by the betrayal of trust that they’re going to feel because a community member here is alleged to have committed these crime.”
Authorities were called after an explosion rocked the 500 block of Elm St in Laurel, about 100 miles (160kms) northwest of Omaha, just after 3am on Thursday morning. Fire crews found Ms Ebling’s body inside the home.
While they were at the scene, law enforcement received reports of a fire at another home three blocks away on Elm St.
There they found three members of the Twiford family deceased.
Investigators said they obtained “physical evidence” at one of the crime scenes that led them to Mr Jones, 42, who lives across the street from one of the fires.
A SWAT team from the Nebraska State Police entered his home in the 200 block of Elm St.
“When he was arrested, it was discovered that he had serious burns over a large part of his body therefore he was airlifted to a hospital in Lincoln. He’s believed to be in serious condition,” Mr Bolduc said at the press conference.
Mr Jones was flown to St. Elizabeth Medical Center in Lincoln for treatment and is in custody at the hospital. He has not yet been charged.
Police believe the two fires were started at the same time and that gunfire was involved in the deaths, KETV reported.