The operation of transmitters designed to jam or block wireless communications is a violation of the Communications Act of 1934, as amended ("Act"). See 47 U.S.C. Sections 301, 302a, 333.
Also LEO data terminals use commercial LTE these days.
Police did it in, I believe, the Bay Area last year, fearing organization of protests
They cut power to cell repeaters. They didn't jam anything, though they certainly got hell for it. The FCC is investigating.
Ahhh, and I didn't know there was an investigation, thanks for that!
"They" in this case was the BART Directors, not the police, and this was not the first time the Directors chose to disable cell service at various stations in the system.