BEIJING, Aug. 18 -- Service of Beijing subway Line 1 has resumed after a signal problem disrupted the operation and stranded rush hour commuters early Thursday morning, the subway operator said.

Spokesman of Beijing Subway Jia Peng said the mechanical breakdown occurred at 7:30 a.m. but was taken care of at 8:40 a.m..

According to Beijing Public Transportation Group, dozens of extra buses were put into operation to carry stranded subway passengers.

The train delay coincided with the work day rush hour and an overnight rain that the city's weather bureau forecast would aggravate to a downpour sometime in the day.

Mobile Internet users posted photos and comments online, complaining about being late for work. Photos of overcrowded platforms and train compartments went viral online, incurring comments of frustration and criticism.

The subway Line 1 runs through downtown Beijing from east to west, carrying up to 1.4 million passengers every day.