A statement issued by Mercedes said Wehrlein struck "two people whom he unexpectedly encountered walking on the closed course".
But an eyewitness has given a different account of the crash.
"I saw exactly what happened," the eyewitness is quoted by TZ.
"The two cars were about three or four feet apart at about 80kph.
"All of a sudden Nico Rosberg just slammed on the brakes. Pascal Wehrlein was surprised. He (Rosberg) obviously did not know which way the course went.
"Wehrlein swerved to the left off the course and then he hit them."