Jansen Panettiere, brother to actress Hayden Panettiere and an actor on series like The Walking Dead and Everybody Hates Chris, has died. He was 28.

Kasey Kitchen, a rep for Jansen’s sister Hayden, confirmed his death to The Hollywood Reporter. The cause of death is unknown and no other details were provided.

Born Sept. 25, 1994, in Palisades, New York, the actor started to make his way into Hollywood in the early 2000s with appearances on popular shows such as Even Stevens, Hope & Faith, Blue’s Clues and Third Watch.

In 2005, he and his sister teamed up for the Disney Channel movie Tiger Cruise, where he plays Joey. The film follows a naval carrier with families on board to join their seafaring relatives on a “tiger cruise.” But the ship is ordered into combat mode after word spreads about the World Trade Center attacks.

Panettiere also had a number of voice acting roles on the big and small screen, including Robots, Racing Stripes, Holly Hobbie and Friends, and Ice Age: The Meltdown. He was also a series regular on the Nickelodeon animated show The X’s.

In 2007, the actor landed the lead role of Luke in Nickelodeon’s original movie The Last Day of Summer, which earned him a Young Artist Award nomination. In the film, his character is resistant to starting middle school and discovers the consequences of wishing he could repeat the last day of summer.

Other TV shows the actor appeared in include Everybody Hates Chris, Major Crimes and The Walking Dead. Panettiere also starred in movies The Perfect Game, 8, Summer Forever, The Martial Arts Kid, Del Playa, How High 2 and Love and Love Not.

In 2015, he and Hayden collaborated again on The Forger, which also stars Josh Hutcherson, Lauren Bacall, Alfred Molina and Scott Eastwood.

Panettiere had a handful of projects in development at the time of his death, including American Game and Horse.