Traffic on a pivotal subway line in Shanghai resumed at noon time Tuesday.

Two subway trains broke down in Shanghai this morning leaving passengers stranded underground for more than?five hours.

After a power trip switch failure, service halted on subway Line One from Shaanxi South Road to Renmin Square at 5:50?a.m.

An accident occurred when a rescue train, which had been sent to fix the power glitch, collided with another train at 7:00 a.m. Partial service resumed at 7:06 a.m.

The subway operating company is evacuating the passengers and dispatched 80 buses to pick them up.

No injuries were reported.

Shanghai Metro has published an apology at its official website.

The cause of the accident is being investigated.

Line One is Shanghai's oldest and busiest subway route. It became operational in 1993 and runs 37 kilometers from north to south.