Kevin Heimsoth tweets thanks to NRA after killing wife, Lynn and dog Sukha

A husband tweeted his thanks for the US National Rifle Association after he said he "killed my whole family".

Kevin Heimsoth, 56, is reported to have killed his primary school principal wife, Lynn, their Golden Retriever, Sukha, and their pet cat in Bellingham, Washington state.

The Bellingham Herald reports that Heimsoth tweeted to the NRA, Donald Trump and Senate Majority Leader Mitch McConnell saying his access to a gun made the murder that much easier.

"Guns don't kill people, people do. Guns just make it a lot easier. AR-15 makes it super easy," he tweeted. "I jsit (sic) killed my whole family, and I couldn't have done it without a gun! I'm too much of a coward, a knife would have been waaay sic too hard. So, thanks to everyone at the NRA".

The tweets were timestamped at 3:09am local time with investigators saying neighbours heard gunshots at around 2:45am on Boxing Day.

The user of the account posted a separate tweet a minute later, which stated: "Moscow Mitch and everyone else for making this possible. Some should call for a welfare check at (address) in Bellimgham WA. Lots of blood … thoe (sic) dog was the hardest".

Heimsoth reportedly turned the gun on himself, however he remains in hospital, news.com.au reports.

Officials at Sunnyland Elementary School said Lynn Heimsoth would often bring Sukha into school to help calm students nerves.

"Lynn was a passionate, equity-driven instructional leader. She loved kids to the core and always kept students' needs at the centre of her work," the school said in a statement.

A vigil was held for the long-time teacher on Friday.