Reddit has removed “a few hundred” Russian accounts suspected of spreading propaganda in the run-up to the 2016 election, according to a blog post by the company’s CEO.

“We have found and removed a few hundred accounts, and of course, every account we find expands our search a little more,” Steve Huffman wrote on March 5. “The vast majority of suspicious accounts we have found in the past months were banned back in 2015–2016 through our enhanced efforts to prevent abuse of the site generally.”

“As it’s an ongoing investigation, we have been relatively quiet on the topic publicly, which I know can be frustrating,” Huffman added. “While transparency is important, we also want to be careful to not tip our hand too much while we are investigating.”

Huffman’s post comes four days after The Daily Beast revealed that Reddit was targeted by the Internet Research Agency — a Russian troll farm that was indicted in February by special counsel Robert Mueller. The Daily Beast report also revealed at least 21 accounts on Tumblr were created by the Internet Research Agency.

Reddit has been notoriously silent on whether or not their site had been infiltrated by Russian propaganda. Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, said in September he was worried that Russian misinformation efforts extended beyond Twitter and Facebook to platforms like Reddit.

On Monday, the Washington Post reported that Senate investigators plan to question representatives from Reddit and Tumblr as part of their probe into Russia’s election meddling.