Personal data "uploaded by millions of Americans onto FaceApp may be finding its way into the hands of the Russian government," a senator said.

FaceApp may have caused a sensation with its filters that can drastically "age" a person in a photo, but it has also come under increasing scrutiny, particularly from Democrats who are concerned about its ties to Russia. On Wednesday, Senate Minority Leader Chuck Schumer called on the FBI and Federal Trade Commission to investigate the data-collecting mechanisms of the Russia-based app — and if the "personal data uploaded by millions of Americans onto FaceApp may be finding its way into the hands of the Russian government."

In a letter to FBI director Christopher Wray and FTC Chairman Joseph Simons, Schumer also expressed concerns that FaceApp, which is headquartered in Saint Petersburg, has "opaque disclosures" of how users consent to providing their photos and data, and how it might be weaponized against the US. "It would be deeply troubling if the sensitive personal information of US citizens was provided to a hostile foreign power actively engaged in cyber hostilities against the United States," he wrote.

Mark Wilson / Getty Images Democratic Senate Minority Leader Chuck Schumer.