Malaysias transportation minister, Wee Ka Siong, told reporters that the accident was the first head-on collision in the 23-year history of the citys Light Rail Transit system.
The trains are automated and typically operate without a driver. But the train that was on a test run was under the control of a driver, the only person aboard.
The authorities said they would investigate whether there was a mistake made at the light rail command center.
We are still investigating the incident, Mohamad Zainal Abdullah, the police chief of the district where the collision occurred, told reporters, but we suspect that perhaps there was a miscommunication from the trains operation control center.
The accident occurred near Kuala Lumpur City Center, an upscale area filled with shops and restaurants, and the Petronas Towers, the citys best-known landmark and at one point the worlds tallest building. The twin towers, the city center complex and the light rail system were key elements of Kuala Lumpurs modernization in the late 1990s under the former prime minister, Mahathir Mohamad.