The trains crashed in heavy fog late Saturday on a single-line track near the village of Hordorf, close to Saxony-Anhalt's state capital Magdeburg, vaulting the passenger train from the track and tipping it onto its side. The front rows of the first passenger compartment were crushed and several seats lay outside the train. Both trains caught fire, but most of the dead were killed on impact, police said.
"The crash was so strong that the passenger train was catapulted off the tracks," Armin Friedrich, the police officer in charge of the rescue efforts, said at a news conference in Hordorf, about 125 miles (200 kilometers) southwest of Berlin, Germany's capital. Nearly 200 police and rescue workers were sent to the crash site.
The cause of the crash was under investigation, and experts said they were still looking at all possibilities, including technical failure and human error. State governor Wolfgang Boehmer, who visited the site Sunday, told reporters one of the drivers may have missed a red traffic signal.
Police said it was too early to comment on a possible cause.
"We are still speechless and shocked by the images and the level of destruction," said Holger Hoevelmann, the interior minister of Saxony-Anhalt.
The passenger train operated by Harze Elbe Express was on its way from Magdeburg to Halberstadt with about 50 passengers aboard, moving at a speed of 62 mph (100 kph), when it crashed with the cargo train, which was going 50 mph (80 kph).
The cargo train, run by Peine-Salzgitter, was carrying calcium carbonate, often used as a calcium substitute or antacid.
Neither train operator could immediately be reached for comment, but the head of Deutsche Bahn, the national German railway, told news agency DAPD that he was "deeply upset" by the accident.
"Of course, we will do everything possible to support all those involved in this accident," Ruediger Grube said, adding that he had contacted Harz-Elbe-Express and offered help.
At the scene, mangled parts of the blue and yellow train passenger were scattered around the field. The dark imprints of some of the bodies that had been removed could be seen on the white frosty ground next to the crash site.
The noise of the collision was heard in the village of Oschersleben, more than four miles (about seven kilometers) away.
Due to the heavy fog, rescue helicopters were not able to fly the injured to nearby hospitals and they had to be taken by ambulance instead. Most of the injured were so severely hurt that doctors fear the death toll could rise, Hoevelmann added.
Several German media outlets said the train driver and a conductor of the passenger train were among the dead, but police did not confirm those reports.
Two bodies have been identified, but police did not want to release their identities before informing relatives. A phone hotline was activated for family members and friends, and psychologists and ministers were on the scene to counsel rescue personnel.
Police said they were having trouble identifying victims because most of them were not carrying ID with them.
Chancellor Angela Merkel expressed her condolences, saying she too was shocked.
"My thoughts are with the families of the victims," Merkel said in a statement.
The chancellor also thanked the many rescue workers for their immediate and tireless help.
In 2006, 23 people were killed in a train accident in Emsland in northern Germany and 101 people died in 1998, when a high-speed train derailed near Eschede in Lower-Saxony.