BEIJING, March 22 (Xinhua) -- China has blocked the rivers flowing through the chemical industrial park ripped by a deadly explosion to prevent polluted wastewater from entering the sea, the Ministry of Ecology and Environment said Friday.

An explosion rocked a chemical plant Thursday afternoon in east China's Jiangsu Province, killing 47 people and leaving 90 others with severe injuries.

The ministry sent a working group to the site immediately after the accident. After on-site inspections, the team decided to block three rivers in the park to prevent the wastewaters from entering the Guanhe river, which flows into the Yellow Sea.

By Friday morning, most of the blocking had been completed, the ministry said.

The working group has ordered that both sewage outlets and rainwater outlets be blocked so polluted water will not seep into the river through rainwater pipes.

Local environmental authorities have launched environmental monitoring to assess air and water quality.