China's Xinhua news agency issued a brief dispatch about the incident in Liaoning province, giving only the site of the crash on Tuesday afternoon in Fushun county and saying a probe was under way.
South Korea's Yonhap news agency, citing an intelligence source in the northeastern Chinese city of Shenyang, said the doomed aircraft was a North Korean helicopter, and that the pilot had been killed.
"The pilot died on the spot," Yonhap quoted the intelligence source as saying, adding that the pilot was the only person aboard the craft.
"The authorities are investigating how the helicopter flew over the border and what the cause of the crash was."
North Korea has a military airbase in the city of Sinuiju, near the border with China.