Authorities say a murder-suicide left five members of a Pennsylvania family dead in their home on Saturday afternoon.

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The victims have been identified as Mark and Megan Short and their three children, Lianna, 8; Mark Jr., 5; and Willow, 2. Officials say all died of gunshot wounds in their Sinking Spring home, roughly five miles outside Reading.

Authorities also found a dead dog at the scene, The Associated Press reported.

As of Sunday, officials hadn't said who fired the shots or given any details about what might have led to the shooting. They did mention that there had been "domestic issues" in the family before. Investigators reportedly found a handwritten "murder-suicide note" at the scene.

Neighbors described their shock at the news, with one telling the Reading Eagle he "never would've suspected there were any issues."

Willow, who was born with a congenital heart defect, had survived a heart transplant at just 1 week old. Her story was highlighted in 2014 by the Eagle, and her challenges in getting necessary medications were covered last year by The New York Times.

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In April, Megan Short wrote a blog post detailing her experiences with post-traumatic stress disorder in the hope that it would help other parents caring for children with chronic medical issues.

"We easily recognize the trauma that our children go through, but we need to acknowledge and work through the trauma that we experience, as well," she wrote. "Trying to heal these wounds isn't easy. Sometimes you will even feel worse during the process, but keep going. It is worth it. Fear and anxiety don't have to control you. You can and will enjoy life again."

This video includes clips from WFMZKWY-TV and WCAU.