Chinese police are investigating the apparent firing of an air gun towards the South Korean Embassy in Beijing.

Authorities say a bullet-proof window at the embassy was cracked around 5 p.m. Tuesday apparently by a small metal ball that was found at the site.

Investigators believe that the metal ball was fired from an air gun, as no gunshot was heard. This is the first time that the South Korean Embassy in China was fired at.

Chinese Foreign Ministry Spokesman Liu Weimin told a regular briefing on Wednesday that Beijing is taking the matter very seriously.