Police in Shandong Province said city workers came across what are suggested to be dozens of Civil War-era bombs while digging for a sewer line on Monday.
Workers called police after discovering two of the aged explosives while digging a 1-meter-deep trench in the provincial capital of Jinan.
Police cordoned off the area as experts continued a search for more buried ordinance.
A 4-hour search produced 40 cylindrical explosives - all about 30 centimeters long and covered with rust, media reports said.
According to a resident living next to the site, the bombs most likely date back to the Chinese Civil War (1945-49) between the Kuomintang and the Communist Party.
"Our family had settled here before the War ended," the resident surname Zhang told the Shandong Business Daily.
Police have removed the explosives from the area and an investigation is underway, Shandong Business Daily reported.
