As investigators try to figure out what caused a house explosion in Pennsylvania that killed six people, their loved ones are reeling from the unimaginable loss.

The explosion in Plum, about 20 miles east of Pittsburgh, was so powerful that it all but leveled the home and started multiple fires at nearby houses. The cause is under investigation, though the homeowners had been having problems with their hot water tank, officials said Monday.

The homeowners, Heather and Paul Oravitz, were the only members of their family known to be inside at the time of the explosion. The four other victims are their neighbors.

Among those killed were a proud father who gave his daughter away at her wedding last month, a super involved hockey mom and dad who never missed a game, and a 12-year-old boy described as a “1,000% momma’s boy.”

Here’s what USA TODAY has learned about them:

Heather and Paul Oravitz

(From left to right) Heather, Cole, Taylor and Paul Oravitz. Paul and Heather were killed in an explosion at their suburban Pittsburgh home, leaving their two children behind. (Credit: Courtesy of Melissa Campbell)

Devoted parents who raised two great kids, Heather and Paul Oravitz were truly special people, said Melissa Campbell, a family friend who began a GoFundMe page for the children, who are 21 and 23 and miraculously were not in the home when the explosion happened.

“The sheer magnitude of the devastation, and the actual event itself, is rather incomprehensible,” she said, adding that everyone who knows the Oravitz family is in shock. “When my mind goes to that place because it’s so unexplainable, I try to focus back on my fond memories of the Oravitzes.”

She recalled getting to know the couple over the years as their sons played in the Pittsburgh Penguins Elite AAA program, culminating in 2019 when the boys won the national championship.

Hockey parents travel all over for games, so they got to know each other well over the years.

“When you play at that level, you travel two or three weekends out of the month and you’re on the road with these folks and they become your family,” she said.

Paul and Heather Oravitz are pictured at one of their son Cole's many hockey games.

She said Paul, 56, and Heather, 51, were “very devoted, very family-focused, dependable and kind.”

“They were someone you could laugh with and someone that would hug you when you needed support,” Campbell said.

She said she started the GoFundMe for the couple’s children, Cole and Taylor, as they struggle with the loss of their beloved parents and begin picking up the pieces of their lives.

Kevin Sebunia

Kevin Sebunia had just experienced one of most dads’ biggest dreams: giving his daughter away at her wedding, according to a Facebook post written by his aunt, Carol Klauss.

The post included a photo of a beaming Sebunia dancing with the new bride at the July 1 wedding.

“We are devastated,” she wrote. “This is a nightmare. It sounds like a cliche to say that Kevin was one of the very best guys we’ve ever known, but it is so true!”

Carol Klauss describes her nephew Kevin Sebunia as "one of the very best guys."

An obituary posted on a funeral home’s website says that friends jokingly referred to Sebunia as “Mr. Home Depot” because of his way with tools and his ability to fix things.

“If someone needed help, Kevin would reply, ‘I’ve got a tool for that!’ or ‘I know a guy,’ and he usually did,” the post reads.