(CNN) -- Nine people are dead, two are assumed missing and 50 seriously injured after a head-on collision between two trains in Germany's southern state of Bavaria, police said Tuesday.
Altogether, 100 to 150 people suffered injuries in the collision, police say.
The crash occurred shortly before 7 a.m. Tuesday local time near the spa town of Bad Aibling, about 60 kilometers (37 miles) southeast of the Bavarian capital of Munich.
Speaking at a news conference, German Transport Minister Alexander Dobrindt said one of the trains had "drilled" into the other, leaving a carriage "totally dismantled." He described the scene as a "horrible picture," saying it was estimated the trains had been traveling about 100 kph (62 mph) at the moment of impact.
The crash occurred on the Mangfall Valley Railway, a single-track regional rail line between the towns of Rosenheim and Holzkirchen, according to train company Meridian.
'We really have no clue'
How the two trains came to collide head-on on a single rail line was still unclear, authorities say, but they are reluctant to speculate too much on whether human or technical error was at fault before data recorders are analyzed.
Two of the three data recorders on board have been recovered so far, said Dobrindt.
He said the collision occurred at a bend in the railway line.
"There's a curve there, so we must assume that the train drivers must not have been able to see each other beforehand," he told reporters.
Christian Schreyer, board chairman for Transdev, which operates the railway, told CNN that it was baffling that the crash could have happened.
"We really have no clue how this could happen," he said. "Both of our trains have been on this track at the same time."
Automatic braking system
The trains were equipped with an automatic braking system that would stop them if they ran through a red signal. Also, each train had a driver and a driver instructor on board.
It would be extremely unlikely for both drivers on a train to miss a red signal -- and then for the automatic braking system not to kick in, Schreyer said.
"We assume that those signals were green, but we don't know yet," he said.
Schreyer said he was still en route to the crash scene from northern Germany, but from what he had heard, the trains were moving at speed when they collided.
"I don't think that (they) were on full speed, but looking at what has happened, they have been not very slow, let's say it that way," he said.
The trains were permitted to run at 120 kph, or just under 75 mph, on the line, he said.
Austrian emergency services called in
Hundreds of police and emergency workers -- from Germany and neighboring Austria -- scrambled to the crash scene, which is in a hilly, forested region.
Helicopters were used to ferry the injured to hospitals and clinics. Authorities said it took about three hours to remove the victims from the scene.
Medical authorities have issued an urgent call for blood donations to help treat the injured, and counselors are being deployed to assist victims and their families.
A journalist at the scene, Stephan Richter of German broadcaster RTL, told CNN that the Mangfall Valley Railway was one of the most important lines in the region, used by workers commuting from Bavarian villages to Munich.
It was a small mercy that the train was not as full as it usually would be, because of a school holiday for the annual Carnival celebration, he said.
"We can only pray right now that the train was not packed out like on a regular basis," he said.
Schreyer said Transdev was shocked by the accident.
"It's really, really rare. We've been running the trains here for 12 years, and we've never had an accident yet."
Meridian said it could not comment on the condition of the train drivers.
German Justice Minister Heiko Maas tweeted his sympathies for those affected, writing in German: "Very bad news from #badaibling. Our thoughts are with the victims and injured. Thanks to the rescue workers."