Witnesses in Gansu's capital Lanzhou said that a strange shining object swept through the sky about 11:30 pm Saturday, followed by earthshaking sounds like bombing. They also reported that an ensuing tremble was felt within 100 sq km around Lanzhou, Xinhua said

One of them, a driver named Zhang, said he he was driving from Lanzhou city to neighboring Yongdeng county when he saw a shining ball with a three-meter-long trail flying from west to east and heard two thunderclaps right after.

The local public security department confirmed they have received more than 700 reports on the case, some saying it was an earthquake, and others saying 'it was an aerolite falling,'  said Xinhua.

The department has sent policemen to search for possible fallen objects but found nothing so far.

Liu Yanan, astronomy professor at the Northwest Normal University, said that it might be a meteorite entering the earth's atmosphere.