Rescuers had to use ladders and cranes to reach the train
The train, which floats on a monorail via a magnetic levitation system called maglev, was going at nearly 200km/h (120 mph) when it crashed near Lathen.
Damaged carriages were left balancing on track 5m (16ft) in the air, hampering rescue efforts.
"Today we are in mourning," said Chancellor Angela Merkel at the scene.
The accident happened at about 1000 (0800 GMT), on a 31.8km (20 miles) test track from Lathen to Doerpenwhich is used for tourist trips and to demonstrate the technology.
It's just unbelievable how human failure can cause so many fatalities so quickly
Martin, Neuss, Germany
Pictures from the crash scene
Emergency workers used fire ladders and cranes to reach the carriages. Several metres below, the ground was strewn with wreckage.
Reports said up to 30 passengers on the train - mostly employees working on the system and staff from a local utility company, RWE.
'Human error'
The maintenance vehicle hit by the train had two crew members.
A spokesman for IABG, the company which operates the train, said the accident had been caused by human error, rather than a technical fault.
The Transrapid system, run by Siemens, is capable of speeds of up to 450km/h (280mph).
The only commercial example of a Transrapid system in operation is the high-speed shuttle to China's Shanghai airport from the city centre.
It was developed by Transrapid International, a joint venture between Siemens AG and ThyssenKrupp.
German Transport Minister Wolfgang Tiefensee, who is in China, has cancelled his trip and is now on his way back to Germany.
In August, a fire broke out on a Transrapid train in Shanghai, adding to concerns about the safety of the technology.
The German companies are keen to make Transrapid an export hit and negotiations are under way about building another link in China, and also in Munich, the BBC's Tristana Moore reports from Berlin.
HOW MAGLEV TRAINS WORK Opposite poles on magnets keep train above track Train is propelled by electro-magnetic system in the sides of the "guideway" instead of onboard engine Top speed (with passengers) - 450km/h (280mph) Developed by Transrapid Int in Germany Operating commercially in Shanghai Test facility in Emsland, northern Germany, is longest of its kind at 31.5km (19.5 miles) Source: Transrapid International
Do you live in the area near the crash scene? Did you witness the accident? Send us your comments using the form at the bottom of the page:
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Here are a selection of comments received so far:
Having used the Maglev train in Shanghai, this should not be used as an excuse to delay further development of this fantastic, environmentally friendly piece of technology. It's apparent that the train hit a maintenence vehicle, thus human error is 100% responsible. This train could offer London - Brighton services in 7 minutes, and further development should continue.Sam, London, UK
What an absolutely tragic and mournful day this has been. Although I'm living several kilometers away from the crash scene, this massive extent of devastation is so gruesome and frightening. It's just unbelievable how human failure can cause so many fatalities so quickly.Martin, Neuss, Germany
I recently rode the Mag Lev train in Shanghai. I've travelled many forms of transit from the underground to Concorde. I came off my round trip feeling very ill at ease - and I remember saying to my friend that if something were on the track at these speeds we would be finished (which is one reason the tracks are elevated). The feeling is very different from the Japan bullet trains or the French TGV. My heart goes out to the family and friends of those killed and injured.David, Santa Monica, USA
I was in the cab of the Transrapid train during a high-speed run at the test track in Lathen on August 18 in connection with my work as a transport journalist. They showed me some of the maintenance vehicles and I can only imagine it would have been a terrible crash if the train hit one of them at speed. It strikes me that the accident does show a weakness in the technology. If a maintenance train were left on the track on a normal railway, it would be impossible to turn the signal behind it to green. There clearly wasn't any such system at Lathen. Robert, London, UK
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Location of Lathen, Germany
Twenty-three people died when a Transrapid maglev train travelling on the system's test track in Lathen in Germany, near the Netherlands border, collided with a maintenance vehicle on the track. Ten others were severely injured according to Karl-Heinz Brüggemann, a spokesman for the rescue effort.

The driverless train was estimated as operating at 170 km/h (105 mph) when the accident occurred around 09:30 local time (07:30 UTC). The unmanned train, with 31 passengers aboard crashed into a maintenance wagon containing 2 workers.

German Chancellor Angela Merkel visited the site to pay her respect to the victims and the rescuers.
File photo of a Transrapid train on its test track
The train had traveled about 1 km (0.6 miles) from its departure station when it struck the maintenance vehicle.  Debris from the accident was spread over a 300 m (984 ft) section of track. Police spokesman Hans Kley confirmed that the Transrapid train did not leave the track, which is elevated approximately 5 metres (16 ft) above the ground. Other reports indicate that the train's roof was torn off in the collision. Rescue workers used ladder trucks from local fire departments to evacuate the stopped train. On hearing of the accident, Germany's Transport Minister Wolfgang Tiefensee suspended his trip in China and made preparations to return to Germany to view the accident scene.

The 31.8 km (20 mile) test system in Germany was built by a consortium of Siemens AG and ThyssenKrupp.  It has been in operation since 1984 and is regularly used by tour groups for demonstration runs four days per week. Transrapid trains are capable of speeds up to 450 km/h (280 mph).  This accident is the first on the system that included fatalities; analysts so far attribute the cause of the accident to a lack of communications between the train operators and the maintenance employees. The only commercial installation of Transrapid technology in service is currently the Shanghai Maglev Train linking Shanghai Metro Line 2's Longyang Road station to Pudong International Airport.