MUNICH, Germany, Feb. 9 (UPI) -- A rare collision between two commuter trains in Germany on Tuesday killed at least ten people and injured about 100 more, officials said -- but the cause of the catastrophe has so far been elusive in the early stages of the investigation.
The high-speed trains were traveling through Upper Bavaria Tuesday morning, officials said, near the town of Bad Aibling when the collision occurred. The scene of the crash is about 35 miles southeast of Munich.
Officials said about half of the injured persons are seriously hurt. The driver of each train was killed.
Investigators said the trains were traveling on the same track when they slammed into each other. Several wounded were airlifted to local hospitals by helicopter, including some in neighboring Austria, because of difficult access to the crash site.
The trains were crowded with morning commuters and vacationers who were on their way to ski resorts and local Mardi Gras festivities. Children traveling to schools are generally on that train, but have a winter break this week. Within four hours of the crash, Munich's Blood Donation Service announced an urgent need for donors.
"We haven't seen such an accident in this region in a very long time, if ever," police spokesman Stefan Sonntag said. "It is terrible."
Authorities aren't yet sure why the trains were riding on the same track.
A transportation official said it's likely both trains were traveling at high rates of speed at the time of the collision because speeds of up to 60 miles per hour are allowed on that portion of the track.
The accident is the latest in a series of train crashes in Germany.
Many European countries have encouraged privately run train systems as opposed to relying on government-run monopolies of rail service. The result has been a patchwork of technology and regulation -- and train drivers, often alone while driving the train, have been increasingly responsible for safety issues.