Beijing is in a heightened state of security Thursday after the local U.S. embassy issued a warning about possible threats against westerners during the holiday season.

"The U.S. Embassy has received information of possible threats against Westerners in the Sanlitun area of Beijing, on or around Christmas Day," according to an alert posted on the U.S. Embassy website and emailed to American citizens in Beijing, according to ABC News.

French, British and other embassies also reported receiving information about possible threats against westerners in the Sanlitun area on or around Christmas Day, and urged their citizens to be vigilant.

By Thursday afternoon, the Beijing police issued a yellow security alert for the Chinese capital and dozens of police, some with rifles, were standing on guard in the area, which is home to a number of foreign embassies and a large shopping center, reported the Evening Standard. Roads leading into the embassy area were closed to traffic.

Per security regulations, the yellow alert is the lowest on a three-tier security warning scale for large stores or shopping and entertainment areas. It is issued in case of receiving threats or finding suspected explosives and is commonly issued during holiday periods, according to the Associated Press.

It's unknown what the origins or nature of the threats were, and its unclear whether the security alert directly correlates to the threats mentioned by the U.S. embassy or simply a precaution due to the time of the year. 

Sanlitun has been the site of violence against Westerners in the past. In August, a sword-wielding man was arrested after mounting an attacking on a French man and a Chinese woman, that left the man injured and the woman dead.