NINGBO -- The death toll has risen to four following an explosion in east China's Zhejiang Province Sunday, authorities said Wednesday.

Two previously missing victims have been confirmed dead after police conducted a thorough investigation at the site of the blast at a demolished factory in Jiangbei district of Ningbo city. The explosion occurred around 8:50 a.m. Sunday.

The two victims were the father and cousin of the man who owned the explosives, surnamed Shan.

Disposal of illegally produced explosives caused the blast, which injured 19 others.

Police found that disposal of the illegally manufactured explosives began at the site Saturday night. Disposal operations resumed at 8:40 a.m. Sunday.

Technicians from the local public security department said they believed errors during disposal operations caused the explosion, and authorities had ruled out the possibility that the explosion was intentional.

Shan was detained by police in Hubei Province Monday. He had previously been wanted by the police on suspicion of illegally manufacturing and selling explosives.

Shan confessed that he had asked family members in Ningbo to destroy the explosives.

Residents affected by the blast have been relocated to two sites. Maintenance work has started in nearby residential communities. Affected residents are expected to receive subsidies after evaluation.