Security has been strengthened at the US Consulate in northern Mexico after two unidentified gunmen opened fire at the building and threw a grenade that failed to explode, the EFE news agency reported on Tuesday.
The two assailants attacked the consulate in northern city of Monterrey on Saturday midnight when it was closed, the consulate said in a statement on Monday.
No one was injured in the assault, which was recorded by the CCTV cameras of the building.
One of the unidentified men fired several shots at the front grill of the building and the other hurled a grenade that failed to explode, the consulate said, expressing "profound concern" over the incident.
The consulate said it had beefed up security and was collaborating with the Monterrey police in their investigation.
According to the police, after attacking the consulate the two men shot up a nearby building housing a department of the Nuevo Leon state government.
Monterrey is the capital of Nuevo Leon and an important industrial and transportation hub.