SHENYANG - A gas explosion in an underground shopping street left more than 20 workers injured in Northeast China's Liaoning province Monday.

The explosion at about 9 am was triggered by a gas leak from underground pipelines at a construction site in the underground shopping street in front of a shopping mall in Shenyang, capital of Liaoning, the city's publicity department said in a statement.

Some 40 workers were at the scene at the time of the explosion.

More than 20 workers, including some seriously injured, have been admitted to two hospitals for emergency treatment, injured workers and their relatives told Xinhua.

Staff of the shopping mall said?that they heard "three huge bangs", felt "strong ground shaking" and saw many workers run out of the tunnel with blood stains on their clothes.

The shock wave of the blast shattered windows of cars and buildings nearby. The explosion could be felt one kilometer away, local residents said.

The cause of the explosion is still under investigation.