Police in Wisconsin are investigating after a man torched a congressman’s district office after the popular social media app TikTok briefly went dark in the United States, according to authorities.

The Fond du Lac Police Department said a 19-year-old man from Menasha admitted to setting a fire at an office space leased to U.S. Representative Glenn Grothman.

Just after 1 a.m. on Sunday, January 19, police said officers along with the City of Fond du Lac Fire Rescue responded to Grothman’s office about a possible structure fire.

Officers found the suspected arsonist near the strip mall shortly after they put the fire out.

The popular Chinese-owned social media platform was shut down on Saturday after the Supreme Court upheld a law to ban the application if it is not sold in the United States.

U.S. users reported being able to regain access to the app following Saturday’s blackout, and by Sunday afternoon, a new message crediting Trump appeared to users.

“Welcome back!” the TikTok message read. “Thank you for your patience and support. As a result of President Trump’s efforts, TikTok is back in the U.S.!”

Earlier Sunday, Trump wrote on TRUTH Social that he is “asking companies not to let TikTok stay dark!” 

TikTok briefly went dark in the United States on Saturday night. (Jonathan Raa / Sipa USA)

“I will issue an executive order on Monday to extend the period of time before the law’s prohibitions take effect, so that we can make a deal to protect our national security,” the president-elect continued. “The order will also confirm that there will be no liability for any company that helped keep TikTok from going dark before my order.”

“Americans deserve to see our exciting Inauguration on Monday, as well as other events and conversations,” Trump said.

His Sunday post did not clarify how soon the extension would take effect or specify how long it would last. 

Fox News Digital’s Danielle Wallace contributed to this report. 

Stepheny Price is writer for Fox News Digital and Fox Business. Story tips and ideas can be sent to stepheny.price@fox.com