BEIJING (AP) — A dozen vessels on Thursday are at work cleaning up about 400 tons of oil that spilled into the sea from a tanker following a collision off one of China’s busiest ports, the maritime safety agency said.

The tanker A Symphony was struck Tuesday by a cargo ship, the Sea Justice, in the Yellow Sea outside Qingdao, southeast of Beijing. The tanker’s manager said some cargo and ballast tanks were ruptured. No injuries were reported.

The Maritime Safety Administration's one-sentence announcement gave no other details.