The official Twitter account of the US Mission in Saudi Arabia had posted a warning to avoid the area that had heavy police presence.
Two teachers have been killed in a shootout at a school in Riyadh, local media reported.
At least two people including an American national were reportedly killed after a gunman opened fire inside a school in Riyadh on Wednesday.
It tweeted: "There has been a shooting at Kingdom School in Riyadh, shooter still at school".
There were no children and teachers at the school at the time of shooting but administration staff were said to be in the building.
The Kingdom School is attended by many children of expatriates living in Saudi Arabia.
Investigators are treating the case as a criminal matter and "not a terrorist incident", the source added.
By late afternoon an AFP photographer observed only one police auto entering the school grounds, which were quiet.
The shooting killed a Saudi and Palestinian.
There was no answer at the school's main office when The Telegraph attempted to call.
The fee-paying school, which teaches a Saudi and global curriculum, has a mosque, health clinic, auditorium and library. Its website says it is a girls' and boys' school from kindergarten through grade 12.
In February previous year a teacher reportedly killed six people at an education department office in the southern region of Jazan.