DALIAN -- An explosion rocked an apartment building in Dalian of northeast China's Liaoning Province Tuesday afternoon, with the exact number of casualties unavailable yet.

The blast broke out at around 5:40 p.m. in Shahekou District of the port city. A Xinhua reporter who happened to be nearby said he heard a loud bang and saw at least three injured people after rushing to the site.

The cause of the accident remains unknown.