Hayden Panettiere: Hollywood Tributes Pour in After Shocking Death

Hayden Panettiere's death sent shockwaves through Hollywood ... and several of her former co-stars are sharing their reactions ... and it's emotional.

Friends and fans flooded social media with messages, including several actors from the 'Scream' franchise -- Hayden's a fan favorite in the slasher flicks.

As we told you ... Hayden was found dead inside a South Carolina residence on Sunday ... and an emergency call was made for an "unresponsive female" in "cardiac arrest." Police say there were no initial signs of foul play and the circumstances surrounding Hayden's death did not appear to be suspicious.

Viola Davis called the actress an "old, wise soul with such a deep heart" ... the two having worked together in the 2016 film "Custody."

Jeremy Renner said, "Bless you and your family ❤️."

After the 911 call came in, the fire department and coroner's office raced to the scene ... and photos show the emergency response ... fire engines, ambulances, and a coroner's vehicle.

Hayden began her career as a child star in TV and film, and was best known for her roles in the hit series "Heroes" and the musical drama "Nashville."

She also landed major roles in other movies like "Remember the Titans," "Raising Helen," "Ice Princess," and "Scream 4."

Hayden was 36.