Shots were fired round 3 a.m. local time into one of the buildings, which housed ICE offices, and around the same time at another building nearby, where an ICE contractor was located, according to the FBI.
No one was injured, though federal employees were inside at least one of the buildings.
“We had federal employees who were present, who although they were not hit by the rounds fired, by the grace of God. Had the bullets gone 2 inches in another direction, we could be here today talking about the murder of a federal official,” said Christopher Combs, FBI special agent in charge for San Antonio, during a news conference.
The FBI has opened an investigation as an “assault on a federal official case,” said Combs. The crime scene is being processed and the FBI is reviewing the surveillance footage.
An unknown number of individuals and vehicles pulled up and “fired numerous rounds into the ICE facility,” said Combs, adding that he doesn’t “think there is a question that they knew which floors the ICE offices were on.”
All of the shots discovered at this point were on the floors where ICE had offices, said Combs.
“To fire indiscriminately into any building, let alone a federal facility, is not an act of protest, it’s an act of violence,” he said. “We are concerned that there could be additional attacks.”
Both FBI and ICE officials raised concerns that political discourse could lead to more violence.
“Political rhetoric and misinformation that various politicians, media outlets and activist groups recklessly disseminate to the American people regarding the ICE mission only serve to further encourage these violent acts,” said ICE San Antonio Field Office Director Daniel Bible in a statement.
That shooting occurred about 4 a.m. local time outside the US Immigration and Customs Enforcement’s Northwest Detention Center, where the man attempted to set the building and parked cars on fire, according to police spokeswoman Loretta Cool.
The July incident occurred about six hours after a peaceful rally against a planned ICE operation at the Tacoma detention center.
CNN’s Catherine E. Shoichet and Ray Sanchez contributed to this story.