JI'NAN, May 23 (Xinhua) -- All 20 people who went missing in an explosive manufacturing plant explosion that occurred in east China's Shandong Province on Monday have been confirmed dead, bringing the death toll to 33, the local rescue headquarters said Thursday.

　　Public security authorities have thoroughly inspected the blast site and all the missing have been confirmed dead through DNA tests, the rescue headquarters said in a statement.

　　The blast, which occurred at 10:45 a.m. Monday at a plant owned by Poly Explosives (Jinan) Co., Ltd. in the city of Zhangqiu, also injured 19 people.

　　The injured are receiving medical treatment at local hospitals and are in stable condition, according to the rescue headquarters.

　　An investigation into the cause of the accident is under way.