Two massive blasts, which happened before midnight on Aug 12, have wreaked havoc on areas a few kilometers away.

The blasts have affected 17,000 households and 1,700 enterprises. At least 6,000 residents have been displaced. Soldiers are combing nearby residential quarters to search for survivors, and their search has covered 6,000 households so far.

A minor explosion occurred on Monday morning at the blasts site. Dark smoke has abated, but flames can still be seen.

Bao Jingling, chief engineer of Tianjin's bureau of environmental protection, said about 700 tons of sodium cyanide stored at the blasts site remain mostly unaffected.

According to He Shushan, vice mayor of Tianjin, as of Monday night, specialists had searched dangerous chemicals scattered within a radius of three kilometers around the blast site's core area. "We have cleaned 150 to 160 tonnes of sodium cyanide."

Environmental authorities set up 27 additional water monitoring spots, three of which were found to contain excessive cyanide, with some samples containing 27.4 times more than the standard. Two of the original waste water monitoring stations also found samples with cyanide levels of 1.25 to 2.2 times the standard.

The city has ordered postal and courier services to stop delivering mail to the Binghai New Area.