According to US media, a man opened fire at the Chinese consulate at about 6 a.m. Tuesday (13:30 GMT Wednesday).
"China is paying great attention to this incident, we officially demanded that the United States find out what happened in this case as soon as possible and take effective measures to ensure the protection of the staff of embassies and consulates of China in the United States," Geng said, according to the statement on the ministry's website.
There were no fatalities in the incident except for the shooter himself and no one was injured.
Local police said the suspect is a Chinese national named Larry Xin Zhang in his 60s living in San Gabriel, a neighborhood popular among Chinese immigrants in Los Angeles, according to a report in the overseas edition of the People's Daily newspaper.
Zhang reportedly lived alone in a rented apartment for over a year. Neighbors said Zhang did not speak much English and could have had difficulties in life due to his inadequate language skills.The police are still investigating the motives behind the shooting.