Texas is suing the city of San Antonio for an alleged violation of the state’s new anti-“sanctuary cities” law, in the state’s first enforcement action against a city under the controversial statute.

The lawsuit, filed Friday in Travis County District Court, centers on a December 2017 incident when San Antonio police discovered a trailer carrying 12 individuals from Guatemala who were suspected of being undocumented. The city’s police department charged the driver with smuggling of persons, but released the migrants without involving federal immigration authorities, as the new law requires, according to the state’s lawsuit.

The 2017 "sanctuary cities" law, known as Senate Bill 4, says police departments can't bar their officers from questioning the immigration status of people they detain or arrest. It also punishes local government department heads and elected officials who don’t cooperate with federal immigration "detainers" — requests by agents to turn over immigrants subject to possible deportation

San Antonio’s police department policy states that officers will not refer individuals to Immigration and Customs and Enforcement unless they have a federal deportation warrant. That policy, the Texas lawsuit claims, “prohibits and materially limits the enforcement of immigration laws.”

The lawsuit seeks hefty civil fees from the city, including a $25,500 penalty for nearly every day that the city’s immigration procedures violated state law. The law went into effect Sept. 1, 2017 — meaning those fees could amount to some $11.6 million.

The lawsuit claims that San Antonio Police Chief William McManus “personally called an immigration attorney from an advocacy organization” and released the individuals without running background checks.

“Unfortunately, some municipalities, such as San Antonio, put the safety of police officers and the public at risk by defying state law,” Attorney General Ken Paxton said in a news release.

City Attorney Andy Segovia took issue with Paxton's characterization of events, saying the attorney general was clearly "aimed at furthering a political agenda."

"While we need time to review the complaint, we are fully confident that neither the city nor Chief McManus violated the applicable provisions of [the law]," Segovia said in a statement. "The city has a long history of cooperating with federal authorities and we will continue to do so. The city’s process for handling human smuggling/trafficking incidents was created in coordination with the federal government, and federal officials have not taken issue with our handling of immigration issues."

Paxton’s office has asked the court to issue an injunction requiring the city to comply with the new law, as well as assess major civil penalties against the city, police department and McManus.

Thomas Saenz, president and general counsel of the Mexican American Legal Defense and Educational Fund, slammed the lawsuit, claiming it had "three obvious purposes: to intimidate and frighten immigrants in the state of Texas, to pressure Texas localities to violate constitutional rights, and to attract public attention for Paxton from the nativist fringe."