A firefighter was hit in the head with a stone and taken to hospital after his crew was attacked by a group of young people.
The crew was tackling a tree fire at a lakeside beauty spot on Monday evening when they were targeted by the yobs, police say.
Pebbles and planks of wood were reportedly thrown at the firefighters during the incident.
The fire, which is not being treated as suspicious, occurred in Shinewater Park in Eastbourne, East Sussex.
Dawn Whittaker, chief fire officer for East Sussex Fire and Rescue Service, confirmed a firefighter was in hospital, as she condemned the "shocking" attack.
She said on Twitter: "I am absolutely disgusted by the fact that our Eastbourne crew were verbally and physically attacked by a group of young people last night when attending a tree fire, we have passed this matter to Sussex Police and I want to be clear that violence of any kind is unacceptable.
"One firefighter taken to hospital after a stone hit him in the head... it's just shocking that people want to harm the very people that risk their lives to keep them safe... very sad."
Firefighters were called to the blaze at 6.11pm and police just after, at about 6.30pm.
Sussex Police said they found no suspects after searching the area.
Anyone who witnessed the incident or may have further information is asked to contact police.
