Beijing police have begun to investigate the Thursday-morning traffic blackout on a section of subway, police sources said on Friday.

During a routine check-up, subway workers drove an unmanned train on the Sihui-Tuqiao subway line early Thursday morning before official operation. But their train could not move further when reached the Guanzhuang station at 6:20 a.m. because of power failure on the tracks.

Hundreds of people who were rushing to work were stranded at the station and were encouraged to take buses instead. Traffic on the subway line resumed at 7:30 a.m.

The investigation has shown that cables connecting Guanzhuang and Balizhuang stations were stolen, causing the blackout on the subway.

The 18.96-kilometer-long Sihui-Tuqiao subway went into operation December last year.

Beijing now has 95 km of urban rail transport in operation, of which, subways make ups 54.15 km. So far, the subway passenger volume accounts for 15 percent of passengers on the city's public transportation, according to information from Beijing Subway Corporation.

Source: Xinhua