Magnussen went off at Turn 8 and slammed into the barriers, causing significant damage to his Haas car.
The Dane looked shaken as he extracted himself from the car but appeared to be uninjured.
"The right-rear suspension broke,” said F1 co-commentator Martin Brundle after seeing a replay of the incident.
Magnussen’s rear brakes then dramatically caught fire but the marshals were able to put it out quickly.
After an initial Safety Car was called, the red flag was flown on Lap 35 to enable barrier repairs to take place.
The race resumed with a standing restart at 9.13pm UK time, and Max Verstappen won.
Haas later confirmed about Magnussen: "He’s at the medical centre and after a check-over is ok, but is being kept a little while longer just for observations."