Tragic ... one of the destroyed trains near Bad Aibling, southern Germany. Picture: AFP/dpa/Josef Reisner

The head-on smash happened in the town of Bad Aibling, on the line between Holzkirchen and Rosenheim, about 60km out of Munich at 7am Tuesday (5pm Tuesday AEDT).

The trains slammed into each other on a curve without braking after an automatic safety system apparently failed to stop them, the transport minister said.

The first rescue units were on the scene within three minutes of receiving emergency calls, but with a river on one side and a forest on the other, it took hours to reach some of the injured in the wreckage.

Rescue crews using helicopters and small boats shuttled injured passengers to the other side of the Mangfall river to waiting ambulances.

Nine people were reported dead immediately while a tenth died later in a hospital, police spokesman Stefan Sonntag said, adding that one person was still missing in the wreckage.

“We have little more than hope of finding them still alive,” he said. “This is the biggest accident we have had in years in this region.”

Horrific ... two trains collided head-on near Bad Aibling, Germany. Picture: AP Photo/Matthias SchraderSource:AP

Tragic ... scores of people have been injured in the horrific crash in Germany. Picture: AP Photo/Matthias SchraderSource:AP

German rail operator Deutsche Bahn said safety systems on the stretch had been checked as recently as last week.

But Transport Minister Alexander Dobrindt suggested a system designed to automatically brake trains if they’ve accidentally ended up on the same track didn’t seem to have functioned properly.

Dobrindt, however, said it was too early to draw conclusions, adding that it was a “horrifying sight”.

“The drivers’ cabs of both trains are wedged into each other. One side of one train is completely torn open. The other train bored into it,” he told a news conference.

“The site is on a curve, we have to assume that the train drivers had no visual contact and hit each other without braking,” Dobrindt said, adding that speeds of up to 100kph were possible on the stretch.

Black boxes from both trains had been recovered and are now being analysed, which should show what went wrong, Dobrindt said.

“We need to determine immediately whether it was a technical problem or a human mistake,” he said.

The two regional trains crashed on the single line that runs near Bad Aibling, in Bavaria, and several wagons overturned.

The two train drivers are thought to be among the dead, and 50 of those hurt were being treated for serious injuries, authorities said.

Each train could hold up to 1000 passengers and are commonly used by children travelling to school, but because of regional holidays to celebrate Carnival, fewer than 200 were on board in total.

“We’re lucky that we’re on the Carnival holidays, because usually many more people are on these trains,” regional police chief Robert Kopp said.

About 700 emergency personnel from Germany and neighbouring Austria were involved in the rescue efforts and about a dozen helicopters were used.

Rubble ... at leats 150 people are injured after the deadly collision. Picture: Josef Reissner/dpa via APSource:AP

Train operator Bayerische Oberlandbahn said it had started a hotline for family and friends to check on passengers.

“This is a huge shock. We are doing everything to help the passengers, relatives and employees,” Bernd Rosenbusch, the head of the Bayerische Oberlandbahn, said in a statement.

In Munich, the city blood centre put out an urgent call for donors in the wake of the crash.

The Munich Blood Donation Service, which delivers blood products to local hospitals, said on its website that there was “an acute increased need for lifesaving blood products” after the accident and called for immediate donations.

Rapid response ... rescue teams transport an injured person at the site of a train accident near Bad Aibling, Germany. Picture: Uwe Lein/dpa via APSource:AP

Germany is known for the quality of its train service, but the country has seen several other accidents, typically at road crossings.

Most recently, a train driver and one passenger were killed when a train hit the trailer of a tractor in western Germany in May, injuring another 20.

In 2011, 10 people were killed and 23 injured in a head-on collision of a passenger train and a cargo train on a single-line track close to Saxony-Anhalt’s state capital Magdeburg in eastern Germany.

Germany’s worst train accident happened in 1998, when a high-speed ICE train crashed in the northern German town of Eschede, killing 101 people and injuring more than 80.

Search mission ... rescue personnel attend an injured person beside one of two trains that collided head-on near Bad Aibling, southern Germany. Picture: AP Photo/Matthias SchraderSource:AP

Fatalities ... rescue personnel carry an injured person near the site where two trains collided head-on near Bad Aibling, southern Germany. Picture: AP Photo/Matthias SchraderSource:AP

Search mission ... firefighters and emergency doctors work at the site of a train accident near Bad Aibling, southern Germany. Picture: AFP/dpa/Sven HoppeSource:AFP