BAD AIBLING, Germany, Feb. 9 (Xinhua) -- The trains must have collided at a "very high speed" and clashed head on, said German Transport Minister Alexander Dobrindt on Tuesday after visiting the scene of the train accident which killed at least 9 people.

According to the latest press release of the local police, a train collision that happened on the single-track railway on Tuesday morning around 6:45 local time in the southern German state of Bavaria has resulted in 9 deaths, with 18 being seriously injured and around 90 severely injured.

The crash site was a "frightening sight", said Dobrindt at a press conference, adding that "one train has bored into the other."

Dobrindt noted that the track is actually backed up with a system that automatically brakes trains when they go on the wrong track. It is still unclear whether technical failure or human error had led to the disaster.

Three black boxes should now be reviewed, he said.

The was a "deviation from the roadmap", said Bavarian Interior Minister Joachim Herrmann at the press conference. However, the reason is not yet fully known.

According to Bavarian police chief Robert Kopp, about 150 people have been sitting in the two trains, as they collided head on. Two people are still missing.

After the train collision, rescue operation is in full swing. Hundreds of emergency personnel are on site, said the local police.