Nico Rosberg admitted his shock after two people were injured during a promotional event the Mercedes driver participated in.
Rosberg was participating at a Mercedes event when another car, driven by touring car driver Pascal Wehrlein, collided with a spectator and a marshal.
According to German daily Bild, the spectator had wandered onto the track and was followed by the marshal. Rosberg slowed his car to avoid hitting the pedestrians, but Wehrlein swerved out of the way to prevent a collision and hit the two people instead.
One of the pedestrians was seriously hurt and was air-lifted to a nearby hospital.
Two members of the German World Cup squad - Julian Draxler and Benedikt Howedes - were passengers in Rosberg and Wehrlein's cars respectively, but were unhurt and trained with the rest of the squad thereafter.
"I am shocked by the accident. My thoughts are with the two people who were injured and I wish them a fast recovery," Rosberg tweeted.
A statement on Mercedes-Benz Motorsport's Facebook page said: "An accident occurred during a visit to the training camp of the German National Football Team: while driving on a closed circuit, DTM driver Pascal Wehrlein injured two people whom he unexpectedly encountered walking on the closed course.
"We cannot offer any statement concerning the severity of injuries, as both injured parties are currently undergoing medical treatment.
"Pascal Wehrlein was uninjured in the accident. We deeply regret this accident and send wishes of quick recovery to the injured. We will work in full cooperation with the authorities in determining the exact circumstances of the accident."