After Carlos Sainz's statement about the stewards' delay for rescue at the Austrian GP, the circuit organization responded, explaining that they acted correctly and followed the rules of the regulations

Carlos Sainz abandoned the Austrian GP last week after problems with his engine. When the Spaniard went to the track's escape area, his car quickly caught fire. In an interview this week, he said he was "surprised that the stewards took so long" to rescue him. It is even possible to see the 27-year-old driver waving to someone to help him.
And the Spielberg circuit organization answered Sainz's question. According to the statement issued, all procedures were carried out according to the regulations.
"Following Jules Bianchi's terrible accident in 2014, the FIA rules regarding rescues and interventions on the track have been drastically tightened," the statement said.
"Intervention is only allowed after instructions from race control. On the one hand, this naturally increases the safety of drivers and commissioners, but on the other hand it has the disadvantage that interventions take a little longer," it followed.

They also explain that the place where the F1-75 #55 stopped was not visible from the race control room. In other words, the stewards were guided by radio only, and when they arrived, there they observed that reinforcements were needed because of the fire.
"The place where Sainz parked the Ferrari was not visible from the stewards' room. They were instructed by radio to go to the car with fire extinguishers and, upon observing the situation, they made the decision to call the fire engine. This decision had to be made within seconds and was absolutely correct. If you remember [Romain] Grosjean's accident, in a situation like this, hand-held fire extinguishers are not enough," he explained.
"Another problem was that Sainz understandably got nervous in the vehicle and released the brakes too early. The wedge had to be put on with the car moving, which obviously made the whole thing extremely difficult. However, because of the strength of the wedge, the car was able to stay stationary on the guardrail. Then the fire was put out," he added.
Although the procedure was done correctly, the organization also admits that one has to learn from accidents like this. "We are a team of motorsport enthusiasts, who sacrifice their free time for training and exercises, to do our best for safety on the track. We will also take this incident as an opportunity to improve further," he closed.