(CNN) -- At least three grenades exploded near the U.S. consulate in Monterrey, Mexico late Friday, a consulate employee told CNN Saturday.
The closest blast was within 40 meters (44 yards) of the consulate, spokesperson Brian Quigley said.
He did not offer many more details, but Justin Davis, a consulate duty officer, said the series of explosions occurred over the course of an hour, starting at 8 p.m. local time.
Davis said there were no reports of deaths or injuries of Americans or any damage to U.S. property, though a few cars in the area were damaged.
Shrapnel injured the watchman of a nearby courthouse, according to the local El Norte newspaper. Another grenade exploded in front of a prison.
That part of Monterrey has a high concentration of government buildings and is often buzzing with police officers, the newspaper said.
The attacks were not believed to be directed against the consulate, Davis said, but, "the proximity in which it happened... is definitely scary to think about."
U.S. officials in the region and security officers were investigating the incident Saturday along with Mexican officials, Davis said.
There were no immediate plans to close the consulate, Davis said.
"We're on guard," he said. "We're prepared and we're ready to address any issues that we need to."