An explosion early Tuesday at a chemical plant in a city on China's east coast has injured two people and left another two missing, according to local authorities.

The blast occurred in Lianyungang Taiyi Fine Chemical Factory in Donghai county in Lianyungang city, Jiangsu Province, a spokesperson for the county government said.

Firefighters are still searching for the missing in the plant, the spokesperson added.

The windows and doors of a school situated 700 meters away from the chemical facility were severely damaged, but no students were hurt as the explosion happened early morning, outside of school hours.

The school's classes have been suspended and will resume Tuesday afternoon.

The explosion caused the leakage of 250 kg of ammonia, which has been diluted with water and will not affect the environment, according to the spokesperson.

Investigation into the cause of the blast is under way.